The 22-year-old joins Neil Lennon's squad until the end of the season after making three appearances in the Italian top-flight this season.
The DR Congolese descent joined Genoa from Avellino in 2017 and enjoyed a fine debut campaign playing 21 matches in all competitions.
His signing comes as a boost for the Hibs who are placed eighth in the league standings with five points adrift of the top six.
“I’m very happy and I’m very excited to get started, to get on the pitch and to fight for the team,” Omeonga told club website.
“I’ve known for a month that Hibs were interested in me. It was that interest that made me come here because they pushed hard and I was happy to know that I was wanted.”
Omeonga has been handed the number 40 shirt and he is available for selection when the Scottish top-flight resumes with a visit Motherwell on Wednesday.
4⃣0⃣| Stephane Omeonga has requested the number 40 shirt and is available to play on Wednesday against Motherwell. pic.twitter.com/JSx3H34ljm— Hibernian FC (@HibernianFC) January 21, 2019