Having started their pre-season with victories over Perth Glory and Leeds United, the Red Devils made it three from three with Mason Greenwood's late goal seeing them overcome Inter in Singapore.
David de Gea came in for his first minutes this summer after recovering from illness, while Luke Shaw was also back from a hamstring problem for a team that showed six changes from the 4-0 win over Leeds.
Ole Gunnar Solskjaer's side had started well in both of their pre-season games this summer and that was again the case against Inter, with Marcus Rashford and Aaron Wan-Bissaka particularly bright early on.
Inter boss Antonio Conte had once again put his faith in 17-year-old Sebastiano Esposito, with the Italian giants lacking options in the final third due to the absence of the controversial Mauro Icardi.
Romelu Lukaku has been strongly linked with a switch to the Italian giants from United - the Belgian again missed out for the Red Devils through injury, though, and is seemingly currently being priced out of a move to Serie A.
It took until the 15th minute for either side to threaten the opening goal, with Shaw sending a powerful strike just wide of Samir Handanovic's post after letting fly from distance.
After a slow start, Inter started to see more of the ball as the first period developed, but the Italians were finding it difficult to get the better of a defence led by the ever-improving Victor Lindelof.
Anthony Martial was next to try his luck as the France international tested the gloves of Handanovic in the 24th minute, before a dangerous low cross from Shaw just missed Rashford six minutes later.
Handanovic then denied Martial from close range down the other end as both sides had opportunities to make the breakthrough before the half-time break in Singapore.
Solskjaer sent the same team onto the field for the second period, while there was just one alteration for Inter at the break as Ivan Perisic - strongly linked with a switch to United last summer - entered the frame.
The Red Devils had a golden chance to make the breakthrough in the 49th minute when an excellent piece of work from Martial saw Lingard eventually strike towards goal, but Danilo D'Ambrosio was on hand to clear off the line.
Solskjaer changed his entire team just after the hour, with Fred amongst those entering the field as the Brazil international was given his first minutes of pre-season.
Ashley Young forced Handanovic into a smart save in the 70th minute, before Tahith Chong just missed the far post with a low strike moments later with Inter struggling to get out of their own half of the field.
United finally made the breakthrough in the 76th minute and it was a wonderful strike from Greenwood, who reacted to a loose save from Handanovic before finding the bottom corner with an excellent finish.
Greenwood almost grabbed a second three minutes later after meeting a brilliant cross from the lively Chong, but the crossbar came to Inter's rescue as the Italians continued to come under fire.
As it transpired, just the one goal separated the two teams at the end of the 90 minutes, but it was another dominant performance from United, who are yet to concede in their three pre-season games.
Solskjaer's side will now head to Shanghai ahead of a clash with Tottenham Hotspur on Thursday, while Inter will continue their preparations for the new season against Juventus in Nanjing on Wednesday.
MANCHESTER UNITED (4-2-3-1): De Gea (Romero 62'); Wan-Bissaka (Dalot 62'), Tuanzebe (Bailly 62'), Lindelof (Jones 57'), Shaw (Young 62'); Matic (Fred 62'), Pogba (McTominay 62'); James (Greenwood 62'), Lingard (Pereira 62'), Martial (Chong 62', Gomes 92'); Rashford (Mata 62')
INTER MILAN (3-5-2): Handanovic; D'Ambrosio, De Vrij (Ranocchia 73'), Skriniar; Candreva (Agoume 83'), Gagliardini (Barella 73'), Brozovic (Valero 83'), Sensi (Mario 73'), Dalbert (Pirola 73'); Esposito (Colidio 83'), Longo (Perisic 46')body check tags ::