There were 25 minutes on the clock before either side had their first real opening, and it fell to the hosts as Odion Ighalo failed to properly connect with a header from Jose Holebas's cross when well placed.
That began an encouraging period for Watford as they pushed for an opening goal, with Thibaut Courtois being called into action for the first time moments later when he collected Sebastian Prodl's header from a corner.
Chelsea finally threatened for the first time shortly after the half-hour mark when Diego Costa sent a shot on the turn narrowly wide as he looked to give his side the lead against the run of play.
It was the visitors who had the first chance of the second half too, with Oscar seeing a shot blocked before John Obi Mikel's effort on the follow-up deflected off a defender and needed to be turned over by Heurelho Gomes.
Troy Deeney and Holebas then both sent shots off target for the home side before Chelsea came forward again, this time Costa reaching the byline before Oscar turned his cut-back wide of the target from close range.
The visitors continued to ask sporadic questions of the Watford defence, with Gomes denying a long-range Nemanja Matic volley before getting down well to turn an Oscar effort around the post.
He was forced into a more testing stop with just over 10 minutes remaining, however, when Branislav Ivanovic was picked out inside the box and went for goal from close range, only to see Gomes push it behind for a corner.
Eden Hazard was left out of the starting lineup, but his introduction helped to increase Chelsea's threat and he should have provided the opener when Willian's pass across the box went all the way through to him, but his touch let him down and Gomes was able to smother it.
The Watford shot-stopper was keeping his side in the match in the closing stages, and saved his best moment for last as he clawed Costa's header away when the Spain international looked certain to win it late on.
The Hornets held out, however, to move up to ninth in the Premier League table, while Chelsea also climb a place up to 13th. body check tags ::