Coulibaly was on Tuesday unveiled as a Rangers player on a season loan deal from French League 1 side Angers.
Concise News understands that the deal is subject to global clearance.
The 21-year-old scored two Serie A goals for the Giallorossi in the 2015-16 season, before loan spells at Bologna and Torino.
"To be honest the plan was to stay at Roma this season but when Steven Gerrard calls you can't say no".
"I am very happy to be here", he told Rangers TV.More news: For 20 years, football wasn't coming home for England boss Southgate
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"When my agent said that Gerrard is the head coach, I said, OK, no problem, and then I was happy to come and join this team. When they asked me if I want to join this team or not, I said yes but I thought it might not really be Gerrard!"
"The manager can help me to develop my football and he is someone who I watched when he was at Liverpool".
Gerrard remains in the market for further reinforcements this summer and a move for Mali worldwide midfielder Lassana Coulibaly is still ongoing at present.
He must now turn his attention to Thursday's Europa League qualifying match against Macedonian team FK Shkupi.
They will become the eighth and ninth signings of Gerrard's tenure, following Scott Arfield, Allan McGregor, Jamie Murphy, Nikola Katic, Connor Goldson, Ovie Ejaria and Jon Flanagan in moving to Ibrox.