The 21-year-old flew into Scotland to complete the transfer on Monday, July 9 before the move was announced by the club on Tuesday, July 10.
Umar who is six foot three inches tall (6ft3in) move to Scotland highly rated, the Nigerian forward was born in Kaduna, he has developed into a lethal goalscorer.
Umar has been on the radar of the new Rangers boss, Steven Gerrard because of his physique, running style and hard work on the pitch.
The AS Roma youngster was spotted by the Italian giants while he was on loan at Serie B side Spezia.
Umar Sadiq talks on joining Rangers because of Steven Gerrard
Speaking on his move Umar revealed that he could not turn down the opportunity to play for a legendary player like Gerrard who wanted to bring him to Scotland.
He said, “It is very good to be here, it has been good so far and I can’t wait to start. I truly am excited to be joining Rangers, it is a historical club and I can’t wait to play here.
“I found out Rangers were interested in me about a month ago when I was on holiday in Nigeria. I got a phone call from my agent and he told me about Rangers and I said let’s see what happens.
“To be honest the plan was to stay at Roma this season but when Steven Gerrard calls you can’t say no.
“He called me about two weeks ago and from there I started changing my mind. Even if the plan was to stay at Roma I couldn’t turn him down.”
Umar also discussed what the move meant for the progression of his career especially after an impressive loan spell at Eredivisie
He said, “He told me about the team; even though I already knew about Rangers and that they are the most successful team in the world.
“He told me about the players and said everybody would be at my side if I came here to help me and he would also help me to go forward in my career.
“We didn’t talk that much about how the team or I would play it was all just Rangers, Rangers, and Rangers.”
Umar who is Gerrard’s ninth signing, with a player of Nigerian descent among the summer recruits.
He will hope to get clearance to be able to participate as soon as possible to participate in their Europa League clash against FK Shkupi to be played on Thursday, July 12.