Luis Enrique's team had their lead at the summit cut to two points last weekend when they let a two-goal lead slip in a draw 2-2 at Sevilla.
Barca rediscovered their devastating best form with an emphatic 3-1 UEFA Champions League triumph at Paris Saint-Germain in midweek – Luis Suarez starring with a dazzling brace.
And Suarez picked up where they left off at Camp Nou on Saturday by firing Barca ahead after 55 seconds.
But the anticipated dominant display did not follow as Valencia spurned numerous chances to equalise, most notable when captain Dani Parejo had a penalty saved and Andre Gomes struck the post.
Barca recovered their poise after half-time and Lionel Messi netted his 400th goal for the club in stoppage time, putting pressure on nearest rivals Real Madrid, who host Malaga later on Saturday.
Barcelona goalkeeper Claudio Bravo spared his team-mate's blushes by saving and holding Parejo's tamely struck effort.
The early setbacks did not dent Valencia's confidence – Nicolas Otamendi heading just wide at the far post before Paco Alcacer turned wide from close range and Javier Mascherano produced a vital 22nd-minute block to thwart the same player.
Barca played with far greater control after the restart, although Neymar and Messi were unable to make acrobatic efforts count.
The Camp Nou's other hero of the afternoon, Bravo, displayed excellent reactions to deny Rodrigo following a 75th-minute penalty box scramble.
