The Belgian has made a permanent return to Goodison Park, where he scored 15 league goals on loan from Chelsea last season.
The 21-year-old spent last season on loan at Goodison Park, scoring 15 Premier League goals, and has now made his move permanent after not featuring in Blues boss Jose Mourinho's plans for the new campaign.
Everton made a breakthrough in agreeing to terms on a deal for the Belgium international - a fee that eclipses the previous €19m club-record signing of Marouane Fellaini.
Lukaku, who enjoyed an extended break after his World Cup exploits with Belgium, was thought to be eager to be reunited with Roberto Martinez, under whom he flourished last season.
Chelsea have already moved to overhaul a front line that misfired last campaign, with Diego Costa joining from Atletico Madrid and club legend Didier Drogba returning on a one-year deal.
More to follow...