Ighalo has found the net 15 times already this season but the Nigerian was unable to break the deadlock at Vicarage Road, with the best chance of the game seeing him head over from six yards in the second half.
The stalemate does little for either side's league ambitions as Watford remain ninth in the table while Bournemouth stay 15th, five points above the relegation zone.
England's assistant manager Ray Lewington was watching on from the stands at Vicarage Road, perhaps to check on Troy Deeney ahead of Euro 2016, but the Hornets captain, like his strike partner, struggled for his usual potency on his 250th appearance for the club.
Deeney and Ighalo have scored 22 of Watford's 29 league goals so far season but if Quique Sanchez Flores' side have any ambitions of carrying their excellent campaign into the European spots, they will need both to regain form fast
In their last 18 combined appearances, the duo now have only four goals between them
Ighalo and Deeney both went close to breaking the deadlock early on as first Ighalo motored away from both Steve Cook and Harry Arter but his shot was saved, then Deeney skewed wide from Juan Carlos Paredes' cross.
Bournemouth suffered a blow when Junior Stanislas hobbled off clutching his thigh in the 23rd minute and he was replaced by Max Gradel, the Ivorian forward who joined the Cherries in the summer but has been out since August with a knee injury.
The visitors were struggling to convert possession into chances although Benik Afobe was unfortunate not to go through one-on-one after he was flagged offside, with replays suggesting he was level.
Composure in the final third was lacking at both ends as the second half began, with Josh King blazing Matt Ritchie's cross over the bar before Watford's Nordin Amrabat air-kicked a half-volley inside the box, much to the away fans' delight.
Bournemouth now looked the more likely to end the stalemate as Arter unleashed a fizzing drive on the hour, which drew an excellent save from Heurelho Gomes at full stretch.
Watford, however, held on and should have won it in the 67th minute when Amrabat dug out a cross from the byline but Ighalo, unchallenged, headed over from six yards.
The Hornets forward continued to pose a threat but his usually pin-point finishing also continued to desert him, as he sliced a right-footed shot high and wide with 14 minutes left.
It was the last time either side looked like stealing a winner as an underwhelming contest ended honours even.
Source : PA
Source: PA