The Moroccan, who joined on loan from Championship outfit QPR during the January transfer window, scored the first goal of the game 12 minutes in and helped to create the second as Milan won at Sampdoria in the league for the first time since October 2007.
Taarabt opened the scoring early in the first half, poking home at the second attempt after being picked out by Adil Rami's right-wing cross.
The roles were reversed just before the hour mark, Taarabt's delivery eventually finding the Frenchman to nod home at the back post after Giampaolo Pazzini had challenged home goalkeeper Angelo Da Costa for the ball.
The result continues Milan's recent resurgence, with the San Siro outfit having now taken 13 points from Clarence Seedorf's six league games in charge.
And it was the two men who kept their place from Wednesday's defeat that combined for the opening goal on 12 minutes.
After an open first 20 minutes, goalmouth action became increasingly scarce as the half wore on, Riccardo Saponara's volley narrowly over the crossbar in the 39th minute the closest either side came before the break.
Samp made a brighter start to the second period, but Rami doubled Milan's advantage in controversial circumstances in the 58th minute.
Lopez, introduced 15 minutes earlier, saw red in the 72nd minute as Samp's frustrations boiled over though Eder showed some positive play, only to be denied twice by Amelia in the final stages.
