Watford looked full of confidence from the first minute, and carved out two early opportunities for Ighalo, but both efforts flashed wide of the target.
The Nigerian forward did not wait long to get his first goal of the match though, and after just nine minutes Ighalo opened the scoring with a strike placed between the legs of Daryl Janmaat.
Ighalo continued to look dangerous though, as the striker tested Newcastle goalkeeper Tim Krul, before rounding the Dutchman minutes later to score his fourth goal of the season.
After the break the hosts began to take control of the match, as Thauvin had a shot blocked, before Sissoko headed wide from a Janmaat cross.
Newcastle pulled a goal back on 62 minutes through Janmaat, who ran into the box before beating Gomes with a cool finish.
The Dutch defender almost scored a second goal moments later, as Gomes produced a stunning save to keep out a decent strike.
The hosts missed two opportunities to equalise soon after, as Siem de Jong headed wide from a Janmaat cross, before Thauvin flashed a shot wide.
Newcastle youngster Rolando Aarons could have snatched a point for his side before the final whistle, but his strike from distance was pulled well wide of the net. body check tags ::