The Stoke City striker trained with the Boro squad for the first time this morning and he is expected to make his debut in Saturday's visit of Nottingham Forest to the Riverside Stadium.
Kitson, who moved to Stoke in a £5.5m in the summer of last year from Reading, has been allowed to leave the Britannia Stadium despite leading their scoring charts with three goals this season.
"I'm happy to be here and to be part of it," said Kitson. "I'll do my best and hopefully that will be enough to keep the club in the top positions.
"I have not had a chance to see Middlesbrough's games but I know I have got some great talent in the squad so I'm looking forward to it."
Kitson scored 54 goals in 111 starts for Reading before moving to Stoke last year.
He is now intent on recapturing that sort of form, having endured injury problems during his short stint at Stoke.
Kitson started his career with Cambridge and he went back to Reading on loan last season, when he scored twice in nine appearances as Reading made the Championship's play-offs.