Cousins threw for 300 yards and led a late rally to tie it, then Dan Conroy kicked a 28-yard field goal in the third overtime that lifted the 12th-ranked Spartans over No. 18 Georgia 33-30 Monday in the Outback Bowl.
Georgia's Blair Walsh became the Southeastern Conference's career scoring leader with a field goal in the second extra period. But he missed a 42-yarder in the first overtime after conservative play-calling and had a 47-yard attempt blocked on the final play of the game.
Michigan State (11-3) ended a five-game bowl losing streak with its first postseason win since beating Fresno State in the 2001 Silicon Valley Bowl. The Spartans overcame a 16-0 halftime deficit and scored the tying touchdown with 14 seconds left in regulation.
The Spartans handed the Big Ten its lone win in three bowl matchups Monday against SEC opponents - Florida beat Ohio State and South Carolina stopped Nebraska.
Georgia (10-4) finished on a two-game losing streak, including a lopsided loss to top-ranked LSU in the SEC championship game.
Cousins led a 10-play, 85-yard drive without the aid of any timeouts to wipe out a 27-20 deficit on Le'Veon Bell's second touchdown of the game in the closing seconds of the fourth quarter. Cousins threw a 7-yard TD pass to Keith Nichol midway through the period and finished the day as Michigan State's career passing and total offense leader.
Cousins was intercepted in the first overtime, giving the ball to Georgia. After the Bulldogs had a short run on their first play in overtime, coach Mark Richt elected to simply center the ball for a field goal try on third down, and Walsh's kick was wide.
The Spartans' comeback overshadowed a standout performance by Georgia's Mr. Everything, Brandon Boykin. The Bulldogs cornerback scored a safety, returned a punt 92 yards for a touchdown and caught a 13-yard TD pass that helped the Bulldogs take a late lead that one of the nation's stingiest defense couldn't protect down the stretch.
Aaron Murray threw for 288 yards and one touchdown for Georgia. He threw an 80-yard scoring pass to Tavarres King, who had six receptions for 205 yards.
The Bulldogs began their year with losses to Boise State and South Carolina before rebounding to win the final 10 games of the regular season. Georgia led top-ranked LSU early in the SEC title game before being dominated over the last three quarters to lose a shot at a spot in a Bowl Championship Series game.
Michigan State was impressive, too, in recovering from an early-season loss to Notre Dame to finish with at least 10 wins in consecutive seasons for the first time in the program's 115-year history. Cousins leaves as the winningest quarterback in school history with 27, and 37 wins for the Spartans' outgoing senior class is a school record, too.
Boykin tackled Keshawn Martin in the end zone for a safety on Michigan State's first offensive play, converging on the receiver at almost the same time as Cousins' side screen. The 2-0 lead stood for Georgia until Murray made his long TD throw to King, who settled under the perfectly thrown pass at the Spartans 25 and never broke stride to get into the end zone.
Less than two minutes later, Boykin brought Georgia fans to their feet when he settled under Mike Sadler's punt at his own 8-yard line and retreated to the 5 before cutting back toward the middle of the field, finding his way through a maze of defenders and outrunning the pursuit to score on the longest punt return in Outback Bowl history.
Boykin's second TD, finishing a five-play, 81-yard drive fueled by Murray's 53-yard completion to King, put Georgia up 25-20. Murray's 2-point conversion pass to Malcolm Mitchell gave the Bulldogs a 7-point advantage before Cousins went to work and revived Michigan State's hopes.
The Spartans were limited to two first downs and just 72 yards total offense to trail 16-0 at the half. Cousins finally got them on track after the first of Darqueze Dennard's two interceptions set up a nine-play, 48-yard drive that Bell finished with an 8-yard touchdown run.
Dennard's 38-yard interception return for a touchdown threw Michigan State within 16-14, and Cousins' TD pass to Nichol gave the Spartans a short-lived 20-19 lead.