Trailing 41-35 at halftime, the Highlanders outscored the Bears 27-10 to open the second half.
After the Bears were within two, 74-72, with four minutes left, Jaylen Bland made a 3-pointer and UC Riverside (9-5) scored the final seven points to notch its fourth win in a row while the Bears (2-9) dropped their sixth straight.
Johnson, a freshman, picked up his first double-double. Bland added 16 points, though he was only 4 of 13 from the arc. Gentrey Thomas added 17 points on 7-of-8 shooting and Alex Larsson 10 on 5 of 6. The Highlanders shot 53 percent and are at 51 percent during their winning streak.