Smalling will return to Old Trafford after Roma failed to extend his season-long loan or secure a permanent transfer, which would have allowed him to play the remainder of the their Europa League campaign.
The 30-year-old cannot be registered as part of United’s Europa League squad either and said he was “gutted” that his time in Italy had come to an end.
But Solskjaer has been impressed with Smalling’s displays in Serie A and suggested that he could be a valued member of United's first team squad next season.
“I think Chris has shown over his Man United career how valuable he is to Man United,” Solskjaer said. “This season was about him being a regular and showing how good a centre-back he is.
“I wanted to give Harry, Vic and Axel a chance, so we found that was best for him, to go to Roma and play for a year.
“Now he’s coming back and he’s shown this season he’ll be valuable. I’ve been speaking to Chris throughout and I’ve been delighted with his season.”
United are hopeful of reinforcing their defence during the transfer window, with a left-footed centre-back required, though right-winger Jadon Sancho is considered their priority.
Smalling’s United career appeared to be coming to an end when he was allowed to move to Italy last summer but he won plaudits for his performances at the Stadio Olimpico.
The former England international tweeted on Tuesday morning: “I’m gutted that I can’t finish what we started this season.
“To experience the love shown to me in such a short time was extra special and it will not be forgotten. I want to thank and wish all the players and staff the best of luck against Sevilla. Daje Roma!”
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