Making his first start of the season, Brown had 18 points and seven rebounds Saturday to lead the 12th-ranked Tigers to an 82-73 win over No. 10 Illinois in the annual Braggin' Rights game.
Laurence Bowers paced Missouri (10-1) with 23 points and 10 rebounds, while Alex Oriakhi added 13 points and a game-high 14 rebounds. Phil Pressey had 12 points and 11 assists to help the Tigers win their fourth straight in the 32-year-old series.
Brown, a transfer from Oregon, became eligible after the first semester and made his initial appearance Monday in a 102-51 win over South Carolina State.
A blue-chip recruit, he made the most of his first starting assignment Saturday.
"It was fun. I'm part of the family now," he said.
Brown anxiously watched from the sidelines as the Tigers rolled out to an 8-1 record without him. After becoming eligible, he has worked hard to make up for lost time.
"I wanted to prove I could play right away and fit in any way I can," Brown said. "I spent a lot of time practicing and getting used to things and the way they play here.
"Now, I'm finally feeling comfortable."
Missouri used a 9-0 run late in the game to take the lead for good at 70-64. The Tigers held a 58-35 edge on the boards and outscored Illinois 44-24 in the paint.
Illinois, which leads the overall series 20-12, won nine meetings in a row from 2000-08 before Missouri began its winning streak.
Brown triggered a key 9-0 spurt that erased a three-point deficit and put the Tigers ahead 70-64. He had four points and two rebounds during the 2:31 span.
Brown scored from close range off a perfect pass from Earnest Ross to increase the lead to 68-64. Pressey added a short jumper seconds later to complete the run.
Oriakhi, who had his fourth double-double of the season, was impressed with Brown's effort.
"He's unbelievable. He did a little bit of everything tonight," Oriakhi said. "I can't believe he's fit in so fast. He's one of us now."
Brown played in two games at Oregon last season before deciding to transfer. He watched last season's Braggin' Rights game from his home in Oakland and was intrigued by the atmosphere, which annually features a sellout crowd with the fans divided equally between the schools.
"I had visited (Missouri) and really hadn't made a decision, but I thought, if I choose (Missouri), that's going to be a fun game to play in," Brown said.
Missouri coach Frank Haith was more than pleased with the performance of his new addition. He immediately moved Brown into the starting lineup after a 12-point performance against South Carolina State, in which Brown excelled defensively.
"It was all about our balance," Haith said. "And he can do a lot of things."
The physical game against Illinois featured 19 lead changes, 35 fouls and 43 free throws.
"They've got a lot of depth and they've got size," Illinois first-year coach John Groce said. "They're good now. They've got a chance to get even better moving forward."
The Tigers scored 12 of the final 16 points in the first half to take a 41-35 lead into the break. Illinois reeled off eight unanswered points midway through the second half to go up 51-50 on a driving layup by Tracy Abrams. The Illini took their biggest lead of the second half, 64-61, on a baseline jumper by Egwu with 6:43 remaining.
But the Missouri defense took over from there, forcing seven successive Illinois misses. Brown, Ross, Tony Criswell and Pressey chipped in with key baskets.
Illinois managed only three field goals in the final 3:29.