The seattle mariners vs houston astros timeline stretches from occasional interleague meetings into one of the more competitive American League West matchups of the modern era. The rivalry changed dramatically after Houston moved from the National League to the American League in 2013, putting the Astros and Mariners in the same division and giving them far more opportunities to influence each other’s seasons.
The overall history has not been evenly balanced. Through the 2026 games played so far, Houston leads the regular-season series 134-106, according to the Baseball-Reference/Stathead head-to-head record. Seattle, however, has dramatically improved the balance in recent seasons. The Mariners won the season series in 2023, 2024 and 2025, then opened 2026 by taking 9 of the first 11 meetings.
Here is how the rivalry developed, and why some seasons matter much more than others.
The Early Years: 2002 to 2007
Before the teams became division rivals, Seattle and Houston met only occasionally because they belonged to different leagues. The first listed regular-season series in the head-to-head record came in 2002, when Seattle won two of three games.
In 2004, the Mariners again took the season series 2-1. Three years later, the Astros turned the tables in a decisive way, sweeping Seattle 3-0 in 2007. These early meetings were meaningful in the historical record, but they did not yet have the frequency or divisional pressure that would define the rivalry later.
The reason is simple: Houston was still an National League franchise, while Seattle was in the American League. Their schedules provided only occasional opportunities to face one another.
2013: The Rivalry Changes Forever
The most important structural moment in the timeline came in 2013.
Houston moved from the National League to the American League for the 2013 season, becoming the first MLB team to move directly from the NL to the AL. The Astros joined the AL West alongside Seattle, Oakland, Los Angeles and Texas.
That change instantly transformed the Mariners-Astros relationship. Instead of seeing Houston every few years, Seattle now had to deal with the Astros as a regular divisional opponent.
Seattle’s 2013 schedule even featured Houston as the Mariners’ home-opening opponent on April 8. MLB described the arrival of Houston as the addition of a fifth team to the AL West.
The competitive balance, however, would take time to emerge. Houston was entering a major rebuilding period, while Seattle was attempting to return to postseason contention.
2015: The Astros Begin to Become a Power
By 2015, the relationship was becoming more competitive. The Astros won the season series 12-7 and were increasingly establishing themselves as a serious AL West team.
The following years showed how quickly the balance could move. Houston went 11-8 against Seattle in 2016, then dominated the matchup 14-5 in 2017. In 2018, Seattle responded by winning 10 of 19 games.
Those results were important because they introduced a pattern that would define the rivalry for years: one team could control the matchup for an entire season, but Seattle remained capable of challenging Houston when the Mariners were playing well.
2019: Houston’s Most Dominant Season Against Seattle
Few chapters in the timeline are as one-sided as 2019.
Houston went 18-1 against Seattle, winning 13 consecutive games against the Mariners. MLB noted that Houston became only the second team in the divisional era to finish 18-1 against one opponent in a season, matching a mark previously reached by Cleveland against Detroit.
The scale of the domination is striking. The Astros outscored Seattle by a combined 123-62 during those 19 games, according to the head-to-head seasonal record.
For Mariners fans, the season became a symbol of Houston’s control over the matchup. It also helped establish the Astros as the team Seattle had to beat if it wanted to make a serious move in the AL West.
2020 and 2021: A Rivalry Starts to Tighten
The shortened 2020 season reduced the matchup to 10 regular-season games. Houston won seven while Seattle took three.
In 2021, Seattle improved considerably, but Houston still finished ahead in their direct meetings. The Astros won 11 of 19 games.
Seattle finished 90-72 that year and stayed in postseason contention until the final day, showing that the Mariners were moving toward a competitive phase. That development would become critical in 2022.
2022: The Biggest Chapter in the Rivalry
The 2022 season changed the Mariners-Astros rivalry more than any previous year.
Seattle won seven of 19 regular-season games against Houston, but the Mariners also reached the postseason for the first time since 2001. The teams then met in the American League Division Series, producing the first postseason matchup in their history.
The Astros swept the series 3-0. Game 1 ended 8-7, Game 2 finished 4-2, and Game 3 became the defining moment.
That deciding game lasted 18 innings and ended 1-0 when Houston rookie shortstop Jeremy Peña hit a home run in the top of the 18th. MLB reported that the game lasted six hours and 22 minutes and remained scoreless through 17 innings.
The game was extraordinary statistically as well. Eighteen pitchers appeared, while the two teams combined for 42 strikeouts. Mariners catcher Cal Raleigh caught all 18 innings.
For Seattle, it was a heartbreaking ending to an important breakthrough season. For Houston, it was another postseason series victory and another step toward a World Series championship.
2023: Seattle Finally Flips the Regular-Season Script
The 2023 season marked a clear change.
After years of Houston having the upper hand, Seattle finished 9-4 against the Astros during the regular season.
The difference was especially visible in Houston. During the first series there in July, Seattle won the first two games, including a 10-1 victory in which the Mariners scored nine runs in the fourth inning. MLB reported that Seattle entered that point 4-1 against Houston for the season.
A few weeks later, Seattle swept Houston in a three-game series and moved within half a game of the Astros in the American League Wild Card race. MLB noted that it was Seattle’s first sweep of Houston since August 2018.
The rivalry remained important all the way to the final week. Houston beat Seattle 8-3 in a critical September series finale, and the Astros ultimately won the AL West after finishing 90-72, with the Mariners two games behind at 88-74.
So although Seattle won the head-to-head season series, Houston still finished ahead in the division race.
2024: Seattle Keeps the Advantage
Seattle again won the regular-season matchup in 2024, taking eight of 13 games while Houston won five.
One memorable series came in late May, when Seattle defeated Houston on consecutive nights at T-Mobile Park. In the second game, the Mariners scored three times in the eighth inning and took a 4-2 victory after Houston had held a late lead. MLB reported that the result moved Houston 5½ games behind Seattle in the AL West at that moment.
The Mariners finished 85-77 that year, while Houston captured the division. So once again, Seattle’s advantage in the direct matchup did not automatically translate into a division title.
That distinction is important when looking at this timeline. The rivalry is not simply about who won more head-to-head games. It is also about when those wins occurred and whether they affected the AL West race.
2025: The Rivalry Becomes a Division Race
The 2025 season supplied another major turning point.
Seattle won the season series 8-5, but the biggest moment arrived in September when the two clubs were fighting directly for the AL West lead. Going into their crucial three-game Houston series, they were tied at 84-69 and also tied 5-5 in their season matchup, meaning the series could determine the season tiebreaker.
Seattle won the series in Houston and completed a sweep. After the final game, MLB reported that the Mariners had opened a three-game division lead and secured the tiebreaker over Houston.
A few days later, Seattle clinched the AL West with a 9-2 victory over the Rockies. It was the Mariners’ first division title since 2001.
That gave the rivalry a new dimension: Houston was no longer simply the established powerhouse that Seattle was trying to catch. Seattle had become capable of taking control of the division itself.
2026: Seattle’s Strongest Recent Run
The shift became even clearer in 2026.
As of the games completed by September 13, Seattle had played 11 regular-season games against Houston and won nine of them, leaving the Astros with only two victories. The head-to-head record also shows Houston leading the overall regular-season series 134-106 through those games, meaning Seattle’s recent surge has narrowed the gap in the modern portion of the rivalry even though Houston retains the long-term advantage.
Earlier in the year, Seattle won 10 of its previous 11 meetings against Houston by May 14. That victory also clinched the 2026 season series for the Mariners surprisingly early.
The final two scheduled 2026 regular-season meetings are set for September 22 and 23 at T-Mobile Park, giving the Astros an opportunity to reduce the damage before the regular season ends.
The contrast with 2019 is remarkable. Houston once went 18-1 against Seattle in a single season; seven years later, Seattle had already secured a 9-2 advantage in the first 11 meetings of 2026.
Who Has the Overall Advantage?
Looking at the complete timeline, Houston still has the historical edge in the regular season. Through the 2026 games played so far, the Astros lead 134-106. Houston also owns the only postseason series between the clubs, sweeping Seattle 3-0 in the 2022 ALDS.
But the more interesting story is the direction of the rivalry.
Houston dominated several seasons during the late 2010s and early 2020s. Seattle’s breakthrough began with stronger competition around 2021 and a postseason appearance in 2022. From 2023 onward, the Mariners started winning the regular-season matchup more consistently, and by 2025 they had turned those wins into a division championship.
The rivalry therefore has two distinct eras: Houston’s long period of superiority and Seattle’s more recent attempt to reverse it.
Why the Mariners-Astros Rivalry Matters
The significance of this matchup comes from more than geography or tradition. Since 2013, the teams have shared the AL West, which means their games can directly affect division standings, tiebreakers and postseason positioning.
The 2022 ALDS demonstrated that the rivalry can reach the postseason. The 2025 series showed that their regular-season meetings can decide a division race. And the dramatic reversal in 2026 suggests that the balance of power can change again.
For fans searching for the seattle mariners vs houston astros timeline, that is arguably the most important takeaway: this is a rivalry whose meaning has evolved with the competitive fortunes of both franchises.
Frequently Asked Questions
When did the Mariners and Astros become division rivals?
The rivalry became a regular divisional matchup in 2013, when Houston moved from the National League to the American League and joined the AL West.
Have the Mariners and Astros played in the postseason?
Yes. Their first postseason meeting came in the 2022 ALDS, when Houston swept Seattle 3-0.
What was the longest Mariners-Astros game?
The most famous was Game 3 of the 2022 ALDS. It lasted 18 innings and ended with Houston winning 1-0 on Jeremy Peña’s home run.
Who dominated the rivalry in 2019?
Houston did. The Astros went 18-1 against Seattle in 2019, including 13 consecutive victories.
Who has the better recent record?
Seattle has had the stronger recent regular-season results. The Mariners won the season series in 2023, 2024 and 2025, and went 9-2 against Houston through the first 11 meetings of 2026.
Conclusion
The Seattle-Houston rivalry has come a long way from its occasional interleague beginnings. The 2013 realignment created a genuine AL West rivalry, Houston’s 2019 dominance established the Astros as the team to beat, and the 2022 ALDS gave the matchup its first postseason chapter.
Since then, the balance has gradually shifted. Seattle won the regular-season series in 2023, 2024 and 2025, with the 2025 sweep in Houston helping propel the Mariners to their first AL West title since 2001. By 2026, Seattle had taken an even stronger grip on the matchup, winning nine of the first 11 meetings.
Historically, Houston remains ahead. Recently, however, Seattle has rewritten the story. That contrast is what makes the Mariners-Astros timeline especially compelling and gives every new AL West meeting added significance.
