The Toffees signed Alex Iwobi from Arsenal in a £35m deal, with Everton paying £28m up front and £7m to be paid in add-ons.
The Nigeria international signed a five-year contract at Goodison Park. This late move came after Everton failed in their pursuit of Crystal Palace winger Wilfried Zaha, though manager Marco Silva insisted Iwobi had always been one of his targets.
“Alex was one of our main targets for this window and I believe he is a fantastic signing for Everton,” Silva said.
“He is a direct and skilful winger and attacking midfielder who always works very hard for his team.
“He is still young but already with a lot of top-level experience – 100 Premier League matches, more in Europe and many international games.”
Iwobi came through Arsenal academy and made his debut in 2015. He went on to make 148 appearances, registering 15 goals.
He is expected to feature for the Merseyside club when they travel to Crystal Palace for their Premier League opener.