Trailing 4-2 entering the fifth, Los Angeles scored six times to take control.
Abreu delivered a bases-clearing double, putting the Dodgers ahead for good, and after James Loney drew a walk, Ellis bashed a three-run homer.
Ellis finished with four RBI and Scott Van Slyke added a two-run double for the National League West-leading Dodgers, who completed a three-game sweep of the Rockies.
Ted Lilly (5-0) remained undefeated in six starts despite allowing five runs (four earned) on six hits over 6 1/3 innings. The left-hander allowed three walks and struck out one.
Colorado starter Alex White (0-2) was pounded for six runs on five hits before exiting after 4 1/3 frames.
Carlos Gonzalez drove in a pair of runs for the Rockies.