EVANSTON -- D.J. Richardson scored 18 points to lead Illinois to a 62-41 victory over Northwestern on Sunday night.
Tracy Abrams added 13 points off the bench for the Illini (19-8, 6-7 Big Ten), who have won four straight.
Reggie Hearn led Northwestern with 11 points. The Wildcats (13-13, 4-9) have lost three straight and five of their last six.
Illinois scored the first 16 points of the second half after ending the first half on a 10-0 run. Richardson's layup extended Illinois' lead to 45-15 with 13:53 remaining. James Montgomery scored Northwestern's first points of the half on a layup with 13:26 left.
Northwestern shot 25 percent from the field and Illinois shot 43.6 percent. The Wildcats committed 14 turnovers while the Illini had nine.
Illinois avenged a 68-54 home loss to Northwestern on Jan. 17 and matched its total of Big Ten wins from last season.
During their winning streak, the Illini have also beaten top-ranked Indiana, then-No. 18 Minnesota and Purdue.
Richardson has scored in double figures in each of the last eight games, a career-long streak in Big Ten play.
Northwestern's all-time low for points under coach Bill Carmody is 37, which has occurred three times, most recently in 2008 against Illinois. The Wildcats' previous season-low point total was 44 against Illinois-Chicago on Dec. 1. Carmody is in his 13th season at Northwestern.
The Wildcats were 7 of 25 from the field and 2 of 13 from beyond the 3-point arc after halftime. Northwestern reached 40 points with 1:30 left on Tre Demps' layup.
The 10-0 run ending the first half gave Illinois a 29-15 halftime lead. Abrams and Richardson hit back-to-back 3-pointers to finish it.
Abrams led the Illini with 11 points in the first half. Usually a starter, Abrams came off the bench while guard Joseph Bertrand made his second start.
Illinois shot 36.7 percent from the field before halftime. Northwestern shot 21.7 percent.
The Wildcats' first-half total of 15 wasn't their season low. They scored 14 in the first half against Minnesota on Jan. 6. Alex Marcotullio led Northwestern on Sunday with eight first-half points but he was scoreless after halftime.
Illinois led 7-0 before Northwestern scored on Marcotullio's 3-pointer with 16:01 left. After the Wildcats cut it to 7-5, Illinois went on a 9-0 run to lead 16-5. The Illinois extended the lead to 19-9 before Northwestern pulled to within 19-15. The Illini then went on a 10-0 run.
Northwestern has beaten Illinois twice in a season just three times, the last time in 1966.
Northwestern center Alex Olah returned after missing one game due to a concussion. He came off the bench with 16:19 left before halftime.
Without Olah in the lineup, Northwestern's tallest starter was 6-foot-8.
Injuries have limited the Wildcats, who are down to just seven scholarship players. They lost forward Jared Swopshire for the season after he underwent arthroscopic surgery on his right knee last week. Drew Crawford was lost earlier in the season with a shoulder injury.
Still, on Thursday against No. 13 Ohio State, Northwestern led for much of the game before falling 69-59.
The Illini's last conference winning streak longer than three games was a five-game winning streak in 2010.
Illinois leads the all-time series against Northwestern 130-38. The Wildcats had won two straight in the series.