Smith's 37-yarder was called back on a false start. Smith had no trouble with 5 extra yards, giving the Huskers (8-3, 5-2 Big Ten) their third win in four games.
Penn State's Sam Ficken, who missed an extra point in regulation, missed a 37-yard field-goal attempt to open overtime. The Nittany Lions (6-5, 3-4) lost for the first time in three home OT games this season.
The Huskers could have won the game late in the fourth after Ameer Abdullah sprinted for a 60-plus yard touchdown run. But wide receiver Sam Burtch was flagged for a personal foul, wiping out the go-ahead score. Nebraska chewed more time off the clock and settled for a tying 19-yard field goal.
Christian Hackenberg gave Penn State a short-lived 20-17 lead when he found James down the sideline for a 46-yard touchdown pass on the first play of the fourth quarter.
The Nittany Lions, who beat Michigan and Illinois in OT, couldn't send the senior class out winners in the home finale.
Hackenberg hit Robinson in the second half for a 43-yard gain, perhaps the last big home-game gain for the junior wide receiver. A semifinalist for the Biletnikoff Award, the 6-foot-3, 210-pound Robinson holds Penn State single-season records for catches and yards and has put himself in prime position to be a first-round pick in the NFL draft. He has said he will wait until after the season to discuss his future.
Hackenberg threw an interception two plays later and Nebraska converted the turnover into a field goal for a 17-13 lead.
Turnovers and wasted plays on both sides defined this one.
Ron Kellogg III was stripped deep in Nebraska's own territory, and defensive end C.J. Olaniyan was there to recover the fumble. Hackenberg quickly capitalized, fooling everyone on a fake handoff, then sprinting to his right and into the end zone for a 13-7 lead.
Snow was swirling, the band was playing, and the students who braved the cold were going wild.
Kenny Bell sucked the enthusiasm out of Beaver Stadium with a 99-yard kickoff return for a touchdown and a 14-13 lead. Purdue's Raheem Mostert had a 100-yard kickoff return for a touchdown last week. PSU coach Bill O'Brien said he planned no changes to the special teams unit, and Nebraska made him pay.
Kellogg got the chance to lead the Huskers in the first after Tommy Armstrong Jr. was benched. Kellogg completed four straight passes, including a 27-yard TD pass to Quincy Enunwa early in the second quarter for a 7-6 lead.
With leading rusher Bill Belton out with strep throat and a bad shoulder, the Nittany Lions gave the bulk of the carries to Zach Zwinak. He carried six straight times on Penn State's third drive and that put the ball on Nebraska's 2. Hackenberg hit Adam Breneman for the short TD pass and the 6-0 lead.
Ficken's point-after hit the upright and was no good, a costly miss that helped the Huskers keep the 7-6 lead at halftime.
Perhaps the cold weather played a role with shaky hands.
Penn State punter Alex Butterworth dropped the snap and Ficken's weak attempt was blocked. Abdullah fumbled in the end zone late in the second quarter and Penn State recovered. Penn State safety Malcolm Willis recovered the ball in his final home game, a fitting scoop for one of the celebrated seniors.
The harsh penalties the NCAA levied against the program in 2012 in the wake of the Jerry Sandusky scandal included a four-year bowl ban and scholarship cuts. The NCAA gave players an out - they could leave if they wanted without having to worry about transfer rules and play right away.
In the end, 10 players transferred, though more than 90 percent of the team stayed.
The bulk of this year's class stuck it out, a group of players that impressed O'Brien daily with its work ethic, strong bond with the coaching staff, and ability to embrace a leadership role when the program needed them the most.
The seniors ran through a tunnel of teammates and greeted their families at midfield. They earned a video tribute that said the players, "led by your committment, led by your loyalty, by your actions, led by example."