The 21-year-old Nigernian striker, who scored five times in 12 appearances during a loan spell at NAC Breda in the Eredivisie last season, planned to stay at his parent club before the lure of the former Liverpool and England captain enticed him to Glasgow.
The lanky forward has also spent time on loan with Bologna and Torino after scoring twice in six Serie A appearances for Roma during the 2015/2017 season.
Speaking exclusively to RangersTV Sadiq said: "It is very good to be here, it has been good so far and I can't wait to start".
Coulibaly is excited to play under Gerrard but admitted he was not sure if it was a joke or not.
"I found out Rangers were interested in me about a month ago when I was on holiday in Nigeria".
The fans already seem to have given him an interesting nickname but I'll let you discover that for yourselves, I couldn't possible repeat the intimation here!
But with midfield signings being made at Angers across this summer, Coulibaly was going to find first team chances hard to come by, but at Rangers the Mali International will likely be heralded as one to watch throughout the campaign.
"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 Scott Arfield thinks about the players who left Rangers in recent seasons he sees, among them, too many failures.
"He can help me to develop my football". It is an honour when someone talks about Adebayor or Kanu next to me. I hope I can score goals here and to help the team as well.