Johnson believes the Blues have every chance of landing a top four finish this term.
"I think he's doing brilliantly, and I always thought he would do to be honest," Johnson told Betdaq.
"As a player he always liked to know the details in every aspect of the game, whether it was coaching, training or the mental side of it.
"He was always destined to become a manager and a Chelsea manager, but I admit it has come a bit sooner than I expected.
"He has steadied the ship and used the young players, and he has probably found a chunk of ability there that he didn't even know they had due to the transfer ban."