Iowa (16-14, 8-9 Big Ten) has won five of its last eight games. A home victory over Northwestern on Saturday would give the Hawkeyes a .500 conference record for the first time in five years.
Nebraska (12-16, 4-13), which ends the regular season Saturday at Minnesota, has lost seven of eight.
After Gatens hit a 3-pointer, Caleb Walker charged up the crowd when he stormed the baseline for a dunk to pull the Cornhuskers within 34-32.
But Roy Devyn Marble scored his first basket of the night on a jumper to start a 15-3 Iowa burst. Gatens followed with a 3-pointer, Marble hit two in a row from long distance, Gatens dunked and the Hawkeyes suddenly were up 49-35 with 10 minutes left.
Marble and Bryce Cartwright had 11 points apiece.
Brandon Ubel led the Huskers with a career-high 17 points, and Walker added 15.
The Hawkeyes, playing in Lincoln for the first time since 1976, split the season series with the Huskers. Nebraska, in its first year in the Big Ten, won first meeting 79-73 in Iowa City on Jan. 26.
Gatens, a 15.7-point scorer for the season, had averaged 29 points in his previous three games. During those three games he shot 60 percent from the field (28 of 47) and 73 percent on 3-pointers (19 of 26).
He wasn't nearly as hot against the Huskers. The reigning Big Ten player of the week started the game 1 for 6, all on 3-point attempts, and was held to five points in the first half. He wound up 4 for 11, including 3 of 8 on 3s.
Nebraska, which has been woeful offensively all season, came into the game off a 62-34 loss at fifth-ranked Michigan State. The 34 points were the fewest the Huskers had scored since 1948.
Neither team was sharp to start. They were mired in an 11-11 tie 10 minutes into the game before the Hawkeyes created some separation with a 12-4 run. The spurt started when Andrew Brommer zipped a pass from under the basket to Aaron White, who was coming down the lane and finished with a dunk.
White stole the ball from Mike Fox on the other end and drove the length of the floor for a layup, and he scored another inside bucket as the Hawkeyes began to pull away.
Nebraska, which shot a season-low 29 percent against Michigan State, opened 5 of 18 from the field and had two 4-minute stretches without a field goal. They shot 37 percent for the game and were 4 of 24 on 3s.
The Huskers trailed 23-19 at half after the Hawkeyes committed turnovers on their last five possessions. It marked the third straight half the Huskers had scored fewer than 20 points.