Mussina (9-4) pitched six strong innings to match Los Angeles Angels left-hander Joe Saunders for the league lead in victories.
Cleveland's Cliff Lee also had eight going into his start Wednesday night at Texas.
Jeter, Johnny Damon, Melky Cabrera and Hideki Matsui hit RBI singles for the Yankees to back Mussina, 8-1 in his last nine starts.
Jeter's single put New York ahead and gave him 2,416 hits, good for third place on the franchise list behind Babe Ruth (2,518) and Lou Gehrig (2,721).
Mussina has been helped by generous run support and effective bullpen work all season, but the 39-year-old righty took charge himself this time out.
Baffling the Blue Jays with soft stuff and late movement, Mussina struck out a season-high six and walked one in his 259th win - one behind Hall of Famer Ted Lyons for 38th place.
One night after Joba Chamberlain lasted only 2 1-3 innings in his first big league start and Yankees pitchers walked a season-worst 10, Mussina, the old pro, showed how it's done.
He worked around a leadoff double in the fourth and yielded five hits, including Scott Rolen's two-out RBI double in the sixth on his 100th pitch.
It's the 14th time in the past 15 years that Mussina has nine wins before the All-Star break, but this is the fastest he's reached the mark in 18 major league seasons.
Ross Ohlendorf, Kyle Farnsworth and Mariano Rivera each worked a scoreless inning to finish it, helping Mussina improve to 24-12 against Toronto - including 15-5 with the Yankees.
Blue Jays catcher Rod Barajas left in the sixth with tightness in his lower back and was replaced by Curtis Thigpen.
Yankees manager Joe Girardi put the slow-footed Molina in motion from first base on a 3-2 pitch in the third, and it paid off as Molina went to third on Damon's one-out single to left.
Jeter followed with his RBI single, moving ahead of Mantle.
"I could never imagine it," Jeter said before the game.
Always reluctant to talk about his personal accomplishments, the Yankees captain received a huge ovation and finally waved his helmet to the crowd of 51,151 while blowing a bubble as he stood on first base. The fans then chanted Jeter's name, with Bobby Abreu digging in at the plate.
The run ended Litsch's scoreless streak at 18 innings. The right-hander, 5-0 with a 1.67 ERA in his previous six starts, lost for the first time since April 22 at Tampa Bay.
Betemit, starting at first base for ailing Jason Giambi, hit a solo homer with two outs in the fourth. Robinson Cano doubled to snap a 4-for-30 skid, Molina walked and Cabrera's RBI single made it 3-0.
Rolen's double cut it to 3-1 in the sixth, but Molina doubled in the sixth to chase Litsch and then scored on Damon's single off Shawn Camp.
Matsui, the AL's leading hitter, added a run-scoring single in the seventh off lefty Scott Downs.
Litsch allowed four runs and a season-high 10 hits in 5 1-3 innings.
