The Uruguay international was stretchered off during the closing stages of Hull’s midweek defeat to Wolves and the club have confirmed the full extent of the injury.
“The club can now confirm that Abel Hernandez suffered a ruptured Achilles in Tuesday night’s game against Wolves,” the club said on their official website.
“The Uruguayan international went down innocuously inside the opposition penalty box in the latter stages of the Sky Bet Championship clash at the KCOM Stadium and, as a result, was forced to leave the pitch on a stretcher.
“The extent of Hernandez’s injury was confirmed following a meeting with the consultant late (on Wednesday) night and – after undergoing surgery – it is expected that the striker will be out of action for six months.”
The news is a bitter blow to Hull after seeing seven key players depart the club this summer following their relegation from the Premier League.
Hernandez scored only four goals in the top flight last season, but notched 20 in the Championship in the previous campaign and scored a hat-trick in the recent home win against Burton.
Tigers head coach Leonid Slutsky added: “We have lost Abel for six months, which is very, very disappointing.
“For me, Abel is one of the best forwards in the Championship and is a huge player for us.
“It is also a big blow for Abel himself because he had made a very good start to the season and was playing very well for the team.
“We wish him all the very best in his recovery and look forward to seeing him back out on the pitch as soon as possible.”