The former Reds midfielder, who concluded his playing career at Stoke City in the summer of 2019, joined the backroom staff at United earlier this week.
He has been helping to coach our Under-16s since October, but Ole has been impressed enough with his former team-mate to promote him to senior duties.
Fletcher was pictured alongside former team-mate Michael Carrick at his first training session, on Monday, and Solskjaer was keen to point out what the 36-year-old could offer.
“Yeah, I thought Michael and Darren should play in midfield for one of these big games!” Ole joked, in an interview with club media.