The score tied 4-4 in the sixth when the D-backs scored three times -- all with two outs. Didi Gregorius, Martin Prado and Paul Goldschmidt delivered consecutive singles against Cubs starter Edwin Jackson to grab the lead.
After Prado and Goldschmidt moved up on a wild pitch, the Cubs intentionally walked Jason Kubel to load the bases.
That brought up Ross, who lined a two-run single to break the game open.
Wil Nieves went 3-for-5 with two RBI hits as the National League West-leading Diamondbacks took the rubber match of a three-game set.
Corbin (9-0) reeled off his seventh win in seven starts despite yielding four runs on six hits over six innings.
Jackson (1-8), meanwhile, was lit up for seven runs (five earned) on 12 hits in a 5 2/3-inning effort.
Scott Hairston pounded a two-run homer for the Cubs.