The 22-year old Wolves Academy product moves to Cambridge just days after completing a month's loan at Oxford.
Ismail is on his sixth loan spell, having previously been at MK Dons, Burton Albion (twice) and Notts County.
The U's have added a month's loan extension to teenage Everton midfielder Ryan Ledson, who first arrived at the Abbey Stadium in November.
Cambridge were fined £7,000 last month for unwittingly picking Ledson illegally in their League Two defeat by Crawley Town on 9 January, one of his 18 appearances to date for the U's.
Ismail was in line to make an immediate debut for the U's, having been named on the bench for Saturday's home date with Exeter City.
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Cambridge United have signed Wolves' Albania-born winger Zeli Ismail on loan until the end of the season.