The loan, agreed for the full season, gives Coventry City a versatile 18-year-old who can play at centre-back or left-back - exactly the kind of cover Lampard has been chasing since gaps at the back were exposed in the club's opening-weekend loss to Arsenal.
Mfuni's senior experience remains limited to a single substitute appearance for Manchester City, in last season's 10-1 FA Cup demolition of Exeter, but he built on that with eight Championship starts during a loan spell at Watford before injury cut his campaign short.
"I feel blessed to be here, it's exciting. These are moments you dream of and to do it with such a good team and a good squad, I'm looking forward to it," Mfuni said.
Asked what Lampard had told him about his role, he added: "I spoke to the gaffer, he wants me to show what I normally do on the pitch, whether I'm at left-back or centre-back, and for me to keep being me and do what I do."
City have watched Mfuni develop since he joined their academy at eight years old, and his rise since has been rapid: a goal in the 2024 FA Youth Cup final, a Premier League 2 title with the Elite Development Squad, and a senior debut in January that came just weeks before his loan move to Vicarage Road.
Watford had hoped to bring him back this summer, and Sheffield United and Swansea also held talks, but it is Coventry who have won the race for his signature, giving the England Under-19 international his first taste of top-flight football.
The move also reflects City's broader approach to developing academy talent through senior loans rather than rushing prospects into first-team contention prematurely. With competition for central defensive minutes intense at the Etihad, a season in the Premier League with a club prepared to trust him is viewed internally as the ideal next step.