Adrian Wojnarowski of ESPN first reported the news.
Jemison joins the Grizzlies after completing a 10-day contract with the Washington Wizards. He made two appearances with the Wizards after signing on Jan. 20, recording one rebound in just over one minute of playing time.
He played with Phoenix in summer league and was with New Orleans in training camp. He was with the Birmingham Squadron in the G League prior to signing with the Wizards, averaging 10.9 points, 11.9 rebounds, 1.8 assists and 1.5 blocks on 55.6% shooting from the field in 25 games.
Jemison 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 last month and was viewed as one of the top 10-day contract candidates.
He projects to have the opportunity to log extensive minutes as the Grizzlies deal with several injuries. The team was forced to sign Matthew Hurt via a hardship exception on Monday in order to have the league minimum of eight players available to play in a loss to Sacramento.
Jemison is eligible to be with the team for up to 10 days or three games.