The news was first reported by Michael Scotto of HoopsHype.
Jemison started the year in the G League with the Birmingham Squadron, averaging 10.9 points, 11.9 rebounds, 1.8 assists and 1.5 blocks in 25 games. He signed a 10-day contract with the Washington Wizards on Jan. 20 and then joined the Grizzlies on a 10-day contract on Jan. 30.
The Grizzlies were able to sign Jemison to a two-way contract after they upgraded rookie GG Jackson to a standard contract. They also have Jacob Gilyard and Scotty Pippen Jr. signed to two-way contracts.
Jemison is averaging 5.8 points, four rebounds and 1.3 blocks on 47.6% shooting from the field in four appearances with the Grizzlies. He produced his best outing on Tuesday in a loss to New York: 12 points, six rebounds, two assists and two blocks.
The 24-year-old emerged as one of the top frontcourt players in the G League this season with the Squadron. He generated plenty of buzz among teams at the G League Winter Showcase in December and was viewed as one of the top call-up candidates.