The Brazilian joined from Atletico Madrid last month for a fee believed to be in the region of £15m, and he insists that there was never a chance of him rejecting Chelsea as soon as their interest was made clear.
"I played a lot against him, I know the difficulty and I think all the players want to work with him," the Evening Standard quotes Luis as saying. "Players grow and give their best. He squeezes and gets the best out of each player.
"I had other offers this summer but from the moment Chelsea entered into contention, I did not think twice. I wanted to change countries and England has always been my priority.
"I had a dream to work with Mourinho and Chelsea have won many titles in recent years. It was very easy for me to decide."
Luis was a second-half substitute as Chelsea beat Valencia 2-0 on Tuesday night.