The Blues have signed Filipe Luis, Diego Costa, Cesc Fabregas and Didier Drogba for a combined £75 million, and Thibaut Courtois has returned from a three-year loan spell at Atletico Madrid.
Yet despite claiming he is happy with the squad at his disposal, Petr Cech has been told he is free to leave, whilst Mourinho says the there could still be more movement this transfer window.
He told reporters: "The market is open and experience tells us all that when the market is open and you can never say what is going to happen. You know if a player has a different reaction in this last part of the month, we never know if any club tries to do something with your players.
"But the reality is that I'm very happy with my squad. I'm very happy with my club and the structure that supports me."
Goal understands the Blues have made an enquiry as to the avilability of QPR forward Loic Remy in the wake of an ankle injury picked up by Didier Drogba while a move for teenage goalkeeper Ivan Brkic is also close to completion.
But Mourinho explained that he is very pleased with the players he has already brought to the club in the off-season while also admitting that his side will be in the running for the Premier League title in 2014-15.
"We have bought some key players having analysed our squad and we believe. These new players bring us to another dimension.
"Yes we are a title contender. If you want me to say we will win the league I can't, because I respect this competition."
Chelsea begin their pursuit of the title against Burnley at Turf Moor on Monday.