The Nigerian striker's incredible form in the Championship last season, when he scored 20 goals in 38 appearances, prompted big-money interest from Hebei China Fortune.
But Ighalo opted instead to sign a new five-year contract with the newly promoted Hornets.
And the 26-year-old has transferred that form to the Barclays Premier League, with his double in the 2-0 win over West Ham on Saturday taking his tally to seven goals so far this term.
Hornets boss Quique Sanchez Flores said: " Ighalo took a very important decision to stay at Watford
It was a brilliant idea
"He is a wonderful man who stayed here because his future here at Watford is really big
He is already an important player for us."
Ighalo opened the scoring shortly before half-time when he got a toe onto Nathan Ake's cross, although the ball was helped on its way by Hammers defender Aaron Cresswell
But if there was any doubt over that goal, there was none about the second after the break when he controlled Ikechi Anya's ball into the area and crashed his shot high into the West Ham net
A second win on the bounce lifted Watford up to ninth in the table, and Ighalo is more than happy with their progress.
"We know (West Ham) are a very good team but we stuck to our game-plan and what the gaffer told us to do, and it really worked," he told Hornets PlayerHD.
"We really pushed ourselves and we took the chances that came, so we are very happy about the game
"I'm happy about my goals, but I'm most pleased about the team performance
We played very well and we deserved the win and the three points.
"We've been performing great this season and we've been working hard together.
"The team have been pushing
We run for each other, we fight for each other, and it's been great."
The Hammers looked a shadow of the side who have beaten Arsenal, Liverpool, Manchester City and Chelsea this season, and manager Slaven Bilic is demanding an immediate response against Everton next Saturday
"That is what we have to do," he said
"Nobody likes to be beaten, and not like this
We gave them a hand and they took the opportunity.
"We paid the price, but let's be sure we can work as hard as them to win a Premier League game."
Source : PA
Source: PA