The build-up to the game had been overshadowed by the horrific terrorist attack at the Manchester Arena and a United win was a fitting tribute to the victims.
Davinson Sánchez's own goal 17 minutes into the game opened the scoring in a comfortable victory against an inexperienced Ajax side. The young defender's shin diverted Paul Pogba's effort into his own net.
Henrikh Mkhitaryan then clinched the result two minutes into the second half when he flicked Chris Smalling's header towards goal.
Pogba goal the highlight in first half
José Mourinho side had the first chance when Marcus Rashford flicked Matteo Darmian's throw into the path of Juan Mata, who was running towards the left byline. The Spaniard, stretching to keep the ball in play, flashed the ball across goal and where Marouane Fellaini was inches away from heading in the game's opening goal.
Ajax were patient with their passing, looking to pass between the lines in United's formation. The Dutch giants had the first shot on target following the first of many passing moves when Chelsea loanee Bertrand Traore fire towards Sergio Romero's near post but the Red Devils' cup goalkeeper had his angles covered.
An intriguing, end-to-end start was rewarded with the first goal just seventeen minutes into the game. Jaïro Riedewald's poor throw-in was intercepted by United in the final third and Fellaini passed to Pogba, who strode forward before his left-footed effort deflected in via Sánchez's shin with the ball seemingly going wide. André Onana had no chance having already dived to his left and was forced to watch as the ball agonisingly loop high into the centre of the goal.
United were the better team in the opening stages despite their opponent's superior possession. Antonio Valencia, captaining the side, could have doubled the lead when he surged past Riedewald before firing straight at Onana.
Taking the lead seemed to take the pressure off the English side and they were comfortable for the next 20 minutes. United were happy to sit back and allow Ajax to pass the ball in front of them, while not allowing gaps between the midfield and defence where Traore tried to find space. When United won possession, they tried to find Rashford in either channel as quickly as possible.
This tactic almost worked five minutes before half-time when Rashford was chasing down a ball alongside Sanchez and the 20-year-old defender attempted to chest the ball back to his goalkeeper but played the ball short, getting away with his error at the last moment with a last-ditched tackle.
Mkhitaryan flicks home to secure victory
United needed just two minutes two double their lead in the second half. Smalling headed Mata's corner towards goal and Mkhitaryan instinctively hooked the ball over Onana from within the six yard box.
Sánchez then proved why he is so highly rated across Europe, with many big clubs, including Chelsea, keeping a close eye on the youngster. The Colombian produced a wonderful tackle, sliding across the wet surface to prevent Rashford from having a free run at goal.
Fellaini almost headed in a third for United, who were simply a level above their inexperienced opponents. Mourinho's side were resilient after scoring the second and limited Ajax to shots from range which failed to threaten Romero's goal. Hakim Ziyech had the best of these opportunities, cutting inside from the right but blasting high and wide. The 24-year-old then had a free-kick which almost summed up his side's frustrating evening, striking the ball into his own player before United easily cleared.
Mata was lucky to escape from a foul on Matthijs de Ligt with just a yellow card after a lunge on the 17-year-old. However, the Spaniard and his side battled on and eventually secured their first European title since their Champions League success in 2008, although could have added a third when substitute Jesse Lingard broke away, only to be denied by the impressive Sánchez.