Egyptian striker Mido has joined Middlesbrough from Spurs in a £6m move.
Mido has struggled for first-team opportunities at Spurs
The 24-year-old forward has signed a four-year contract with Boro after agreeing terms and passing a medical.
Boro, who have lost their first two league games, have gained a work permit for Mido, who is in the squad for Saturday's game against Fulham.
"I played against him as a player and he always impressed me" said Boro boss Gareth Southgate. "He's got good technical ability - he's a goalscorer."
Southgate added: "When you've got one of the best crossers of the ball in the league in Stewart Downing, you want someone like Mido who can head the ball."
Sunderland and Birmingham had also expressed an interest in Mido, who had fallen further down the pecking order at Spurs with the arrival of Darren Bent in a £16.5m move from Charlton this summer.
Birmingham tried to revive a deal for Mido after their initial efforts failed in July because of stipulations in the contract.
Sunderland manager Roy Keane may now opt to turn his attentions towards his former Manchester United team-mate Andy Cole.
Mido, who has also played for Ajax, Marseille and Celta Vigo, joined Tottenham on loan from Italian Serie A side Roma.
He scored 11 goals in 27 league starts during the 18-month loan spell, prompting Spurs to make the move permanent.