Roberson set a single-game Kansas State rushing record for a quarterback, breaking Michael Bishop's previous mark of 198 against Missouri in 1996.
The highlight of Roberson's day was a 91-yard touchdown scamper late in the first quarter, the longest run by a Kansas State player in 54 years.
The special teams also got into the act as defensive back Marcus Patton blocked a punt that Jerad Johnson recovered in the end zone for a touchdown that made it 21-3 with with five minutes left in the first half.
From 1969-1997, Nebraska won 29 straight against Kansas State, but the balance of power has shifted in recent years. The Wildcats have won three of the last five meetings and Saturday was their most lopsided win ever against the Cornhuskers.
While Kansas State (9-2, 5-2 Big 12 South) reached nine wins for the ninth time in 10 years and kept alive its slim conference title hopes, Nebraska's pride suffered another blow.
One of the most impressive streaks in NCAA history is in jeopardy as the Cornhuskers (7-5, 3-4) may need to beat Colorado the day after Thanksgiving to be assured of avoiding their first non-winning season since 1961, the last time they lost as many as five games.
Nebraska's string of 33 consecutive nine-win seasons also is being threatened. The last time the Cornhuskers failed to win at least nine games was 1968, when they went 6-4.
Kansas wore down Nebraska by rushing for 415 yards on 57 carries.
Darren Sproles ran for 155 yards and three touchdowns -- all in the second half -- and set a Kansas State record with his seventh straight 100-yard game.
Down 21-6 at the half, Nebraska's defense tried to turn around the game early in the third quarter, forcing fumbles on Kansas State's first two possessions of the second half.
The Cornhuskers converted the first turnover into a 35-yard touchdown run by JamMal Lord but could not take advantage of the second as Josh Brown's 29-yard field goal attempt caromed off the right upright.
The Wildcats responded with a seven-play, 80-yard drive, taking a 28-13 lead on Sproles' eight-yard run. Nebraska aided Kansas State with 25 yards in penalties during the possession.
Nebraska had one more chance to get back in the game, but the Cornhuskers were turned away when Lord was stopped for a three-yard loss by linebacker Terry Price on fourth and one from the Kansas State 11 with three minutes left in the third period.
The Wildcats put the contest away on Roberson's 25-yard run early in the fourth quarter, then continued to pour it on as Sproles added touchdown runs of 12 and 70 yards to complete the rout.