Cech has been Chelsea's number one keeper since arriving in the Premier League in 2004 but his position is under threat following Courtois' return to Stamford Bridge after three years at Atletico Madrid.
The 22-year-old Belgium international earned rave reviews during his time in Madrid, winning the La Liga title last season as well as helping the club to the UEFA Champions League final.
Courtois has publicly declared his intention to be Chelsea's first-choice gloveman ahead of the 2014-15 season, putting him on a collision course with veteran Cech, who is rumoured to be considering his options.
However, Mourinho said he is pleased with the situation.
"To have Cech and Courtois means we have the best young goalkeeper in the world and one of the top-three or five most experienced keepers," the Portuguese boss said.
"For me and Chelsea, it's perfect. Maybe one of them won't be happy but the Chelsea supporters will be happy and they're more important than players.
"Of course, the window is the window, but I'm so happy with the situation.
"If we don't have good players, we're in trouble. I'm paid to make decisions and I'm really happy with the situation."
Chelsea open their Premier League campaign away to newly promoted Burnley on August 18.
