Walker was chosen as club captain by the players before the start of the season.
Guardiola said: "Same guy, involved not as captain. Now the players pick him. More responsibility if there are problems in the locker room he has to resolve it. I'm really pleased for him."
On being England captain last month, he added: "I'm sure he'll be happy, born in this country and represent the country. Harry Kane is the captain, he's not a young lad anymore, lots of experience and titles.
"He can show it."