The Croatia international scored twice in last week's 3-2 home win against Udinese, including a last-gasp strike, and netted the only goal in Saturday's (AEDT) clash with Brescia.
Milan are now unbeaten in five matches in all competitions this calendar year but they also had Gianluigi Donnarumma to thank for this latest victory.
Donnarumma made a number of big saves at 0-0, paving the way for Rebic to fire in the winner with 19 minutes remaining as Milan maintained their upward momentum.
Without the suspended Mario Balotelli against his former club, Brescia nearly opened the scoring 34 minutes in when Florian Aye forced Donnarumma into a low save.
Zlatan Ibrahimovic had a header kept out earlier in the half and was guilty of missing a sitter five minutes before half-time, the veteran striker somehow failing to find the target from six yards.
Ernesto Torregrossa sent an acrobatic scissor-kick volley just wide and then had a goal ruled out for offside, moments after Dimitri Bisoli's near-post shot was saved by Donnarumma.
Donnarumma was proving to be the busier of the two keepers and he did well to stop two more Torregrossa efforts in quick succession.
It was Milan who opened the scoring with 71 minutes on the clock, however, as Ibrahimovic's cutback was not dealt with by Brescia and Rebic fired home the loose ball from five yards.
Samu Castillejo had a goal disallowed for an offside infringement late on and Theo Hernandez hit the crossbar, though it did not matter as Milan saw things through.