Cesc has been outstanding since joining Barca in the summer.
Walcott said: "He was an absolutely fantastic player for Arsenal, throughout the years he was with us he went up so many levels. Now he puts on a Barca shirt and it just seems to suit him.
"He was fantastic in an Arsenal shirt, but I think it just looks right and it's where he always wanted to be in the end. That's where he started and he's fitted into the team really well, he's scoring goals and enjoying himself."