Essien came on as a substitute in Saturday's 1-0 Premier League win over Sunderland, having spent six months on the sidelines after rupturing a cruciate ligament in his right knee during pre-season training.
"It's been a long while but I'm always positive and I knew I would come back stronger," the 29-year-old told Chelsea TV.
"That's what I did and I was happy to be on the pitch again."
It was his third major injury in three years after also missing most of the 2008-09 season and half the following campaign with ligament damage in both knees.
Essien, who is in contention to start Chelsea's game at Norwich on Saturday, added: "It's always good to be back after such a long injury, so I'm very happy to be back."
The Ghana star, who did not return in time to make his country's African Nations Cup squad, said they decided to play it safe before making his latest comeback.
"We didn't rush anything, we take every day as it comes," he said.
"My physios and doctors are there for me, I've been working hard and I think the hard work has paid off."