Guice had 73 yards rushing and also had a 75-yard kickoff return for LSU (8-3, 5-3 Southeastern Conference), which ended a three-game skid.
Fournette, who was one of Miles' prized 2014 recruits, finished the game owning LSU's single-season rushing record at 1,741 yards, surpassing the mark of 1,686 yards set by Charles Alexander in 1977.
Inside Death Valley before kickoff, the crowd roared when coach Les Miles was introduced during Senior Day ceremonies. The coach tipped his trademark baseball cap to acknowledge the crowd, raising the volume a little more. As the clock wound down, fans serenaded the coach by chanting his name.
Miles' overall record improved to 111-32. LSU could have had a nine-win regular season if not for lightning canceling the season opener against heavy underdog McNeese State.
There were a handful of pre-snap penalties and the passing game was largely ineffective. Brandon Harris was 7 of 21 for 83 yards, no touchdowns and an interception. A number of his passes sailed over intended receivers or skipped off the grass short of their mark. Most of his receptions came on check downs to running backs, including a critical third-down swing pass to Fournette for a 17-yard gain that sustained the Tigers' final scoring drive.
LSU's frustrations on offense were encapsulated by the opening possession of the second half, which began on the A&M 25 after Guice's long kickoff return in which he broke more than a half-dozen tackles before finally getting pushed out of bounds.
Hindered by a false start and a sack, the Tigers had to settle for a 46-yard field goal try, which Trent Domingue pushed wide right for the kicker's third miss of the game.
When the Tigers finally got a big play to take a 13-7 lead, it came on Guice's long run.
Thanks largely to Fournette, LSU drove into field goal range four times in the first half, but Domingue, who'd missed one field goal attempt all season coming in, missed two of four in the first half.
That allowed Texas A&M to take a 7-6 lead into halftime. The Aggies' lone score came on Allen's 8-yard, third-down pass over the middle to Ricky Seals-Jones.
The Aggies squandered a chance to widen their lead when Allen was sacked and stripped by Kendell Beckwith on the LSU 13, with the Tigers' Devon Godchaux recovering.