Nolito hit a post before grabbing a brace as Celta ensured they are now mathematically safe from relegation.
Valladolid, on the other hand, remain deep in trouble with Juan Ignacio Martínez's side lying second from bottom and three points off safety.
Nolito put the hosts ahead on 38 minutes before their lead was doubled inside a minute when Charles, who had also earlier struck the woodwork, pounced.
Nolito grabbed his second of the night just after the half-time break and a Stefan Mitrovic own goal just three minutes later did for the visitors.
They did manage to pull one back, through Manucho with a quarter of an hour remaining, but it was nothing more than a consolation on a night that belonged to rampant Celta.