Nebraska can clinch the Legends Division title - and a berth in the conference championship game against Wisconsin on Dec. 1 - with a win at Iowa on Friday or a Michigan loss at Ohio State Saturday.
Martinez passed 36 yards to a wide-open Bell for the Huskers' first touchdown, and they later connected for a 30-yarder along the sideline.
Minnesota had 98 total yards entering the fourth quarter. Nebraska pulled its starters, and the Gophers scored on MarQueis Gray's 1- and 6-yard runs.
The Gophers finished with 177 yards. Philip Nelson was 8 of 23 for 59 yards, with two interceptions, for Minnesota.
Bell and Jamal Turner had career highs for catches and yards for Nebraska. Bell had nine for 136 yards and Turner six for 83.
Ameer Abdullah went over 1,000 yards for the season, finishing with 79 yards on 18 carries. Rex Burkhead, an All-Big Ten pick a year ago, went through warm-ups but did not play in a fourth straight game because of a left knee sprain.
Imani Cross, the Huskers' dependable short-yardage back, scored on runs of 3 and 1 yard.
The Huskers went unbeaten at home for the first time since 2001 and won a fifth consecutive conference game for the first time since 2009, when they were in the Big 12.
Coaching great Tom Osborne joined Bo Pelini in leading the Huskers onto the field before kickoff. Osborne also was honored during a halftime ceremony on "Salute to Tom Osborne" Day at Memorial Stadium.
Osborne, who won 255 games and three national titles from 1973-97, is retiring as athletic director Jan. 1.
Nebraska took control early, with Martinez sharp and the defense holding the Gophers to 60 yards in the first half.
The Huskers tried to land the knockout punch going into halftime, but the Gophers stopped Cross for no gain on second-and-goal from the 1 as the clock ran out.
Bell's second touchdown, followed by Stanley Jean-Baptiste's 48-yard interception return, put the Huskers up 38-0 late in the third quarter.
Martinez completed his first six passes and finished 21 of 29. He increased his career passing yards to 6,140, passing Zac Taylor's mark of 5,850 yards in 2005-06.
Martinez's two TD passes give him a Big Ten-leading 21 for the season.
It was a mostly stress-free afternoon for the Huskers, who had to overcome double-digit, second-half deficits to beat Wisconsin, Northwestern, Michigan State and Penn State.
Nebraska took a quick 10-0 lead, and Minnesota crossed midfield just once on its first eight possessions.