Chicago led through captain Jeff Larentowicz's 66th-minute penalty, which was controversially awarded even though replays indicated Juninho's foul on Quincy Amarikwa was outside the penalty area.
But the lead lasted only six minutes before Robbie Rogers intercepted Chris Ritter's pass and set up Donovan to finish at the far post.
It followed a brace in the 4-1 win over the Philadelphia Union, which made him MLS' all-time leading goalscorer. For Chicago, the result was a seventh draw in 12 games this season.
In the late matches, Colorado Rapids made it back-to-back wins with a one-sided 3-0 victory over Houston Dynamo. Deshorn Brown scored a first-half double in the fifth and 35th minutes, with Kamani Hill rounding off the scoring six minutes after the interval.
The win lifts Colorado up to third in the Western Conference standings, one place ahead of Vancouver Whitecaps who edged out Portland Timbers 4-3 in an entertaining affair.
Portland led after just three minutes through Maximiliano Urruti, but the Whitecaps hit back in style thanks to two penalties from Pedro Morales (16 and 26) plus further strikes from Erik Hurtado (45) and Jordan Harvey (49).
Replies from Gaston Fernandez (77) and Will Johnson (86) set up a nervy finale but Vancouver held on to extend their unbeaten run to four matches.