Victory for Charlton was of vital importance in this match as they try and make up ground in a bid for automatic promotion and they got off to the perfect start with a goal after just 15 minutes when Zhi Zheng's cross was headed on by Andy Gray for Darren Ambrose to score from close range.
Charlton looked on course for the three points when they went further in front on 36 minutes. Greg Halford's fierce low cross being turned into his own net by the former Charlton player Danny Shittu.
Charlton had a lucky escape in injury time in the first half when Jobi McAnuff's long-range shot hit the foot of the post and was scrambled away.
Watford made an immediate change after the interval, bringing on John-Joe O'Toole and he immediately brought the visitors back into the match, scoring with an easy chance after Charlton had tried to play him offside.
Within two minutes, Watford had levelled when Shittu made amends for his earlier mistake by scoring at the right end for his team, powering home a close-range header from a corner.
Watford, who have won ten games away this season and would have gone back to the top of the table with a victory, looked the more likely to get the winning goal as Charlton got nervous and McAnuff and Nathan Ellington both went close for the visitors.
So the stalemate still leaves Charlton in a play-off position, but seven points behind Watford, who are now level on points at the top with Stoke City.