Jason Kendall hit a tiebreaking double in the seventh inning to back Blanton and lead the A's over the Mariners 4-3.
The 24-year-old Blanton got his 12th victory of the season, tying the A's rookie record set by Chris Codiroli in 1983 and setting a team record for a rookie pitcher with his 33rd start, one more than Matt Keough in 1978.
Blanton pitched 201 1/3 innings this year.
"That was the only goal I set for myself all year," he said. "I just wanted to make all my starts."
Trailing 2-1, Oakland came back in the seventh after Julio Mateo (3-6) relieved George Sherrill with two outs and none on.
Marco Scutaro doubled and scored on a single by Mark Ellis, who took second on the throw, and Kendall doubled for a 3-2 lead. Scutaro added an RBI single in the ninth against Gil Meche.
Blanton (12-12) won for the fourth time in five decisions, giving up two runs and six hits in six innings. Harden, who hasn't started since Aug. 19 because of a strained muscle below his throwing shoulder, struck out five in two innings, and Street finished for his 23rd save in 27 chances. allowing Yuniesky Betancourt's sacrifice fly.
With runners on second and third, Street struck Raul Ibanez to end the game.
"It was a big win for Joe," said Harden, who made his third relief appearance. "I definitely wanted to shut 'em down for Joe. He's been amazing this season. He's been a big part of this team."
Street recorded his 18th consecutive save, tying the longest streak for an A's reliever since Dennis Eckersley row in 1995. But he got himself in trouble with a pair of walks in the ninth.
"He's been phenomenal for us," Kendall said.
Mark Kotsay's RBI double put Oakland ahead in the first, but the Mariners came back in the third to go ahead 2-1 on Betancourt's two-run homer. which followed a single by Ichiro Suzuki.
"I left it over the middle," Blanton said. "It wasn't a very good pitch."
Suzuki, who reached 200 hits for the fifth straight season on Friday night, went 3-for-4, all singles.
Seattle's Jeff Harris, a 31-year-old rookie, allowed one run and two hits in 5 1/3 innings. Sherrill struck out Dan Johnson with the bases loaded to end the sixth.
Mariners manager Mike Hargrove refused to criticize his relievers.
"The bullpen's been awfully good for us this year," he said.
Seattle's Richie Sexson struck out twice, giving him an AL-leading 165. ... The A's are 11-6 against the Mariners this season. ... Betancourt, a stellar defensive shortstop, committed his fifth error in 59 games this yea. ... The game started with Safeco Field's retractable roof open, but it was closed when it started raining in the sixth. ... Suzuki turned in a defensive gem in the fourth when he made a sliding catch of Eric Chavez's sinking liner to right.