The Portuguese has moved to sign Mohamed Salah from Basle, with Juan Mata's move to Manchester United imminent.
Salah, who must pass a medical and agree personal terms, which is something of a formality, and become Chelsea's third signing of the month after Bertrand Traore and Nemanja Matic.
Traore is an 18-year-old prospect who was immediately loaned to Vitesse Arnhem, while Matic has been thrust straight into the first-team squad after initially departing for Benfica in the deal which saw David Luiz move to Stamford Bridge.
"Hopefully we are done," Mourinho said. "We are not bringing in a striker in this window."
Chelsea's initial intention this month was to solely go for Matic, a defensive midfielder, but circumstances and a fee from United too good to turn down will see Mata depart and Salah come in.
Mata and Kevin De Bruyne, who joined Wolfsburg, have departed for big fees and substantial profits.
Both play in a position in which Mourinho has numerous options.
It is a transitional period for Chelsea, yet they are still challenging at the top of the Barclays Premier League.
Mourinho, whose focus this weekend is on Sunday's FA Cup fourth-round tie with Stoke, said: "We would only have done Nemanja this window if we hadn't lost a player (Mata), but we are trying to keep the level and improve, to improve the team, to improve the squad, to change the style of play.
"And we're still trying to get results and still trying to win matches.
"We need that mixture of young players growing up and experienced players giving stability to the team.
"We are doing that. You can see what we're trying to do. Nemanja is 26, Salah 21, so we are trying to build a team for the future.
"We're doing fine. We're calm. In relation to the domestic competitions, Man City is Man City, an unbelievable level.
"Arsenal have had eight years building this team, and this team is perfect. They're also a strong contender."
Mourinho plans to field a strong team against Stoke as Chelsea bid to continue their fine recent record in the FA Cup.
The Blues have won the trophy in four of the last seven years, beginning when Mourinho won the cup in 2007 during his first spell.
With Fernando Torres out due to a knee injury, striker Demba Ba could be given a first start since October against a team which beat Chelsea in early December.
Chelsea have won six of their last seven, conceding twice, but Mourinho is wary of a repeat result against Mark Hughes' men.
The Portuguese said: "We lost against this team and it was not a long time ago.
"Everybody knows who Stoke is: very physical, very direct, very strong on set-pieces, they come here to compete.
"I expect a very difficult match. That's why I'm going to play with a strong team.
"I'm not going to make big changes in the team, because we are going to try to go as far as possible in the competition. We have to play with a very strong team."