The 21-year-old winger previously spent the 2013-14 season on loan at the Toffees, scoring four goals in 11 starts for the club.
Everton manager Roberto Martinez was keen on another deal for the highly-rated youngster last summer but he joined La Liga club Sevilla instead on another season-long loan, and played 28 times, scoring three goals.
But Martinez is now expected to land Deulofeu on a long-term deal, with Barcelona having a buy-back option for a specific, unknown fee.
Sky Sports’ Spanish football expert Guillem Balague confirmed on Monday: “Deulofeu is going to be transferred to Everton. 3m euros with an option of FCB to re-buy him later on for a price. He didn’t want to go on loan.”
Deulofeu, born in Catalonia, is a product of Barcelona’s youth academy and has represented Spain at every level from U16 to U21, and he made his senior international debut last year.
He has made five substitute appearances for Barca and played regularly for Barcelona B, but has never started a match for the senior team.