Midfielder Miller was called up by Steve Clarke for the first time ahead of a Nations League play-off double-header with Greece.
And Kettlewell believes the player he made Well captain at just 18 years old will shine for Scotland if he wins his first cap.
He said: “We've all seen with Lennon, at such a young age, he's a lad with lofty ambitions and every challenge that's put in front of him he takes on with the greatest of ease.
“He just has that calm nature and clean mind and unbelievable composure. The composure you see on the pitch is something he carries off it as well.
“I'm absolutely delighted for him and he'll embrace the challenge, take in all the teachable moments that will come in the Scotland squad. He will embrace it and his call up is thoroughly merited.
“I'm sure if Lennon gets an opportunity to take to the pitch I would have no doubts about him.
“I selected him in every game he was available for, he took the captain's armband at 18-years-old and you need to be special for that to come your way.
“I never worried about Lennon when I managed him because he's one of the most humble lads I've had the pressure of working with. He doesn't get carried away, doesn't believe his own hype.
“He understands...