The extension to Liverpool's Anfield Road Stand will not be ready for the club's opening home game of the Premier League season against Bournemouth on 19 August.
Construction began in 2021 to add 7,000 seats and increase the stadium's capacity to 61,000.
The entirety of the current stand will stay open during the remainder of its development, as it did last season.
Liverpool start their season away at Chelsea on 13 August.
"This has been a hugely ambitious and complex construction project right from the start and I would like to thank everyone who has played a part," said Liverpool managing director Andy Hughes.