A brace from Nolito, Charles' first-half effort and Stefan Mitrovic's own goal lifted Celta to a comprehensive victory at the Estadio de Balaidos.
Monday's result comes as a timely boost for Luis Enrique's men, who moved 10 points clear of the drop zone to preserve their top-flight status for another season with three games remaining.
The news is not so good for second-bottom Valladolid, with the club firmly entrenched in a relegation scrap, three points from safety, though they have a game in hand.
Valladolid had only won one of their past 23 games away from home and that poor form looked set to continue when the home side scored two quick-fire goals before the half-time whistle.
Nolito was first to get himself on the scoresheet, opening the scoring in the 38th minute with his fourth goal in three games.
And Brazilian team-mate Charles joined in on the action within seconds as Celta doubled their advantage.
It got worse for the visitors after the break as Celta added another two goals in the space of three minutes.
Nolito netted his second only a minute into the second half - back-to-back braces for the Spanish striker - before Valladolid defender Mitrovic bundled the ball into his own net.
Valladolid restored some pride with former Manchester United striker Manucho pulling a goal back inside the final 15 minutes- the team's first goal in three games in all competitions.
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