Mourinho had wanted to sign Wayne Rooney to spearhead Chelsea's title challenge this season, but the Manchester United man will not force an exit from Old Trafford, per Sam Wallace of The Independent, so Eto'o will be brought in as a short-term option.
Eto'o, the 32-year-old Cameroon forward, is taking a huge pay cut from the £17 million a year that made him the world’s best paid footballer at Anzhi Makhachkala and will sign on a free transfer.
However, Anzhi are understood to have sweetened the deal by giving Eto'o a multi-million-pound lump sum to get him off their wage bill.
Despite his rising age, Eto'o still represents a prolific capture for Chelsea, having scored 21 goals in 44 appearances for Anzhi last season.
His understanding with fellow new arrival Willian will help both players settle quickly, and a record of nine goals from 16 European outings last term proves Eto'o can still score goals outside of Russian football.
More importantly for Mourinho, Eto'o is a man who adheres to the tactical side of the game, allowing the Chelsea boss to vary the way he sets up his team.
How will Samuel Eto'o perform at Chelsea?
Capable of playing on the counterattack or receiving the ball with back to goal, Eto'o's finest day under Mourinho for Inter Milan was arguably a 1-0 defeat to Barcelona, which saw Inter advance to the Champions League final. For 86 minutes, he led the Italian rearguard action from the front, constantly offering an outlet for his overworked defenders.
Of Chelsea's current options, the 20-year-old Romelu Lukaku remains naive from a tactical point of view, while Fernando Torres' Premier League goal return of 15 from 84 matches simply isn't good enough for a title-challenging side.
Demba Ba, meanwhile, is the subject of interest from former club Newcastle, who are reportedly in talks to re-sign the striker seven months after he departed, per David Kent of the Daily Mail.