Gennaro Gattuso's side registered a comfortable victory by the same scoreline over their less illustrious opponents in the Coppa Italia on Wednesday, but never came close to another victory in what was a desperately poor display.
Antonio Caracciolo gave the hosts a 24th-minute lead with a powerful header and only a number of smart stops from goalkeeper Nicolas ensured the hosts went into the interval ahead.
Fabio Pecchia's side took full advantage of Milan's profligacy 10 minutes into the second period as substitute Moise Kean slotted home after storming into the penalty area unmarked.
Milan duo Suso and Leonardo Bonucci both squandered excellent opportunities to set up a tense finale before Daniel Bessa, who also came off the Verona bench, added gloss to the scoreline with another cool finish with 13 minutes left.
And Milan's miserable day was compounded when, after a VAR review, Suso was shown a red card for a late challenge in stoppage time, as Verona secured only their third Serie A win of the season in spectacular style.
Defeat for Milan, meanwhile, is their seventh in the league this season and leaves them a whopping 18 points behind leaders Napoli.
After their limp surrender earlier this week, Verona started with a point to prove and scarcely gave Milan a chance to settle with a series of robust challenges in the early stages.
However, it was the visitors who carved out the first clear opening when Nikola Kalinic's curled effort from the edge of the penalty area was tipped around the post by Nicolas.
Verona got the reward their effervescent start deserved midway through the opening period as Caracciolo scored his first goal for the club.
The defender rose highest to meet Romulo's outswinging corner to thump a header against the underside of the crossbar from six yards, which clipped the bewildered Gianluigi Donnarumma on its way into the net.
Milan almost levelled within a minute, but Nicolas was equal to Franck Kessie's powerful drive from just inside the area.
The Verona keeper excelled again shortly before the interval, getting down smartly to repel Suso's effort before Thomas Heurtaux brilliantly blocked the Spain international's follow-up effort.
Kalinic saw a goal-bound effort deflected wide seconds after the restart as Milan looked to claw their way back into the game, but it was Verona who scored next to all-but kill off the visitors' comeback hopes.
Bessa found space down the left and pulled a cross back towards the penalty spot, where fellow substitute Kean was waiting to slot into Donnarumma's bottom right corner for just his second league goal of the season.
Nicolas tipped over Suso's powerful drive and Bonucci headed wide from close range as Milan tried in vain to set up a tense finish.
But Bessa added Verona's third in the 77th minute with a neat finish from 12 yards, Romulo collecting his second assist of the match as part of a flowing counter-attack.
And it got worse for Milan in the first minute of added time when Suso received a straight red card for an ugly, late challenge on Daniele Verde.
Key Opta Stats:
- Verona have won a Serie A game by three or more goals for the first time since April 2014 (4-0 vs Cagliari).
- They have now picked up seven points in their last four league matches after having gained six in the previous 13.
- Milan have lost five of their last eight Serie A away games: they have conceded two or more goals in six outings in the process.
- Milan have won only one of the last six league games against newly promoted teams (D3 L2).
- The Rossoneri have been trailing in seven games in Serie A this season. They have gone on to lose every time.
- Before his red card, Suso was directly involved in 15 of Milan's 30 attempts on goal, thanks to seven shots and eight chances created.