The victory, in UW's final non-conference game and final regular season home game of the season, was the Badgers' 15th in 17 games, improving their season record to 28-21.
UIC (35-24) trailed 6-3 heading into the top of the seventh, but the Flames loaded the bases with one away on three straight singles off Badger starting pitcher sophomore Eden Brock.
Senior Katie Layne relieved Brock but promptly yielded an RBI single to first baseman Lauren Brennan that drew UIC within 6-4. With the bases still loaded, Layne struck out right fielder Becky Moran. But catcher Elizabeth Jacoby was hit by a pitch and second baseman Nikki Rogers drew a walk, bringing in two runs to tie the game at 6-6.
Brock re-entered and retired shortstop Joyce Cathey to end the inning. UW then went down in order in the bottom of the seventh and the teams chose to use the international tiebreaker, with a runner opening each inning at second base.
With two outs in the top of the eighth and a runner at third, Flames third baseman Sara Hernandez smacked a double to left-center to score Cathey from third with the go-ahead run, making it 7-6 UIC.
UW, though, answered when senior catcher Boo Gillette singled home sophomore centerfielder Sam Polito from third with one away in the bottom of the eighth.
Brock (18-8) stymied UIC in the top of the eighth, setting the stage for Phillips' game winning RBI in the bottom of the eighth.
Brock recorded a career-high 10 strikeouts in 8 2/3 innings, including eight in the first four innings. But she allowed 11 hits and six earned runs.
UIC reliever Mercedes Lovato (16-10) took the loss, yielding two unearned runs in 3 2/3 innings. Starter Brittany McIntyre gave up six earned runs in 4 2/3 innings.
UW scored four runs with two outs in the bottom of the fifth to turn a 3-2 deficit into a 6-3 edge. Sophomore second baseman Athena Vasquez capped the rally with a three-run double.
Wisconsin wraps up the Big Ten regular season with games Saturday and Sunday at Minnesota.