A run of 23 winless home league games against the Red Devils stretching 9,941 days came to an end on Sunday as Steven Gerrard's successor oversaw a 3-1 victory in his first match in charge.
Leon Bailey struck and Lucas Digne scored a delightful free-kick within the opening 11 minutes at a rocking Villa Park, where Jacob Ramsey atoned for deflecting in a Luke Shaw strike by scoring a fine effort just after half-time for Emery's elated side.
The Spaniard was recently lured back to the Premier League following a successful stint at Villarreal, which included leading them to a first major trophy when defeating United on penalties in the 2021 Europa League final.
Villa Park erupted at the final whistle, just as it had after Bailey burst through to punish lax defending before Digne bent a superb free-kick beyond David De Gea.
Ramsey provided the first goal and earned the foul that led to the second, before inadvertently scoring an own goal when diverting home Shaw's hopeful strike to reduce the deficit before the break.
The Villa talent's impact did not stop there, though, as the 21-year-old rifled home early in the second half to wrap up victory, becoming only the fourth player in Premier League history with a goal, assist and own goal in the same game.
The result ends United's nine-game unbeaten run in all competitions and sets up an interesting reunion in the Carabao Cup on Thursday.
Emery's side will head to Old Trafford full of confidence after this long-awaited home victory against the Red Devils, who fell behind after seven minutes on Sunday.
Victor Lindelof's hassling of Ollie Watkins took him well out of position and the forward capitalised by playing through to Ramsey, who sent Bailey scampering into the vacant space to hit a superb left-footed low past De Gea.
Bailey danced in celebration after a seventh-minute opener that Villa added to four minutes later.
Shaw was booked for a foul on Ramsey and Digne stepped up to the resulting free-kick, whipping home an outstanding 22-yard strike in front of the Holte End.
It was a wretched start by United that brought up memories of some their other recent embarrassments and Emiliano Buendia threatened to make things worse when curling narrowly wide.
Matty Cash drove a more hopeful effort over as the visitors continued to stutter, although Emiliano Martinez - who played in Emery's final match as Arsenal boss - was called upon for two key saves in the 34th minute.
First the Argentina goalkeeper denied compatriot Alejandro Garnacho scoring on his first Premier League start after the teenager coolly made space to get away a drive.
Martinez then denied Cristiano Ronaldo as the stand-in United skipper saw a powerful diving header saved.
United had created little else but a dollop of luck helped them reduce the deficit in the 45th minute as Shaw's thumping drive struck Ramsey and flew past wrong-footed Martinez.
Donny van de Beek's penalty appeals for handball fell on deaf ears in stoppage time - as, it seems, did Erik ten Hag's last-minute instructions in the centre circle before the second half got under way.
Bailey was allowed through to unleash a shot seconds after half-time and Villa restored their two-goal advantage in the 49th minute.
Watkins drove down the left and Lindelof all too easily allowed him to cutback for the unmarked Ramsey, who superbly struck a first-time shot into the top right-hand corner.
It was a gut punch that United never recovered from and their frustrations began to bubble to the surface.
There was a VAR check for possible violent conduct after Ronaldo and Tyrone Mings wrestled in the box, leading to a melee that saw both players booked but nothing more.
Bailey was left in a heap after Lisandro Martinez appeared to leave something on him.
Ten Hag made changes in a bid to change the dynamics but Villa dug deep, with Emery making alterations to see out a great first win as manager.
It would have been even more memorable had Douglas Luiz succeeded in his attempt to score directly from a corner in stoppage time.