Success on the road is becoming something of a normality for the Eagles since Pardew was appointed in January with the former Newcastle boss guiding them to 11 away wins in 14 games across all competitions.
This victory will not rank among the most memorable of those but Yohan Cabaye's second-half penalty was enough to lift Palace up to sixth in the Premier League as the Eagles repeated their Championship play-off final heroics against the same opponents in 2013.
Zaha had been slammed by Pardew for a poor performance in the defeat at Tottenham last weekend that saw the England international hauled off at half-time.
The 22-year-old, who also won the penalty that Kevin Phillips converted to earn Palace promotion at the Hornets' expense two years ago, was more impressive in the Capital One Cup victory over Charlton on Wednesday but was relegated to the role of substitute at Vicarage Road.
Still, he proved his worth to both Pardew and Palace as he came on with just under half an hour remaining and bamboozled Allan Nyom into tripping him just inside the box, with Cabaye tucking away his second of the season from the resulting penalty.
When asked if he was pleased with Zaha's display after he replaced Bakary Sako, Pardew replied: "I am.
"I thought his reaction in the week was very good, I told him on Thursday he wouldn't start despite playing well on Wednesday
He took that well and has reacted in the right way.
"This is a lesson learned for him, he can't let his standards slip, especially with Sako and (Yannick) Bolasie
I can't play them all and competition is fierce."
With the likes of Sako, Bolasie, Zaha and Jason Puncheon, Palace have a number of flair players with pace to burn - but Pardew was pleased with the more workmanlike performance that saw his side halt a run of two league defeats.
"From a manger's perspective it was a great day for me and my team," he said.
"The concentration levels were really high today
There was some really good wide play and in the end that won us the game.
"I don't smile often but I do smile today because I was really pleased, it wasn't our greatest performance but it was a good, professional performance and as manager of the team that makes me happy."
For Watford, this was a first home defeat since their return to the top flight as they also conceded their first goal of the campaign at Vicarage Road.
Manager Quique Sanchez Flores has enjoyed a strong start to life with the club but refused to blame the penalty for costing his side anything from a match in which they failed to hit the heights of recent wins against Swansea and Newcastle.
"We didn't lose today because we conceded a penalty," he said.
"We lost today because we didn't play well and Crystal Palace played better than us
We didn't have a good performance.
"I'm not satisfied with the performance, we always try and do our best and create attempts but sometimes it is impossible
At half-time we tried to change something but it was a normal match other than the penalty."
Source : PA
Source: PA