The club announced the jersey number on its website on Friday.
Iwobi joined Everton from Arsenal for £34m on Thursday on a five-year deal with the move seeing him become the most expensive Nigerian player in history.
“New signing Alex Iwobi will wear number 17, the same number he wore at Arsenal, while Richarlison moves to seven, Michael Keane to five and Dominic Calvert-Lewin to number nine,” Everton said on its website.
The Everton No. 17 jersey was worn last season by Senegalese, Idrissa Gueye, who moved to PSG for £29m last month.
Romelu Lukaku also wore the number when he was on loan at Everton from Chelsea.
Other players who have worn the number are Muhamed Besic, Tim Cahill, Scot Gemmill, Francis Jeffers, Gareth Farrelly.
Signup for FREE news updates, latest information and hottest gists everyday