Liverpool FC have officially opened the stadium's new Main Stand, increasing the overall capacity to 54,074.
The £100m expansion work has added a third tier for supporters, boosting Anfield's crowd capacity by about 8,500.
Work began on the stadium last year and the club said it marked another "incredible chapter".
The expansion work is part of a wider £260m regeneration of the Anfield area of the city.
The redeveloped stand now houses about 20,500 seats and is the new home for the Hillsborough memorial.
Manager Jurgen Klopp said "it's so impressive" and "one of the nicest stands" he has ever seen in his life, adding that it "should be an advantage" for the team.
He urged fans to make lots of noise at the first game in the newly expanded stadium on Saturday when the Reds host Premier League champions Leicester.
Club owner John W Henry had a tour on Friday along with LFC legends Kenny Dalglish, Ian St John, Ian Rush and Jamie Carragher.
Two public spaces near the stadium were renamed 96 Avenue and Paisley Square last month in memory of the Hillsborough victims and former Reds manager Bob Paisley.
The Hillsborough memorial has been repositioned in 96 Avenue after being moved for 18 months to Liverpool Cathedral while the work was finished.
Further work is planned on the Anfield Road Stand to add a further 4,800 seats and bring capacity up to 59,000.
The history of Anfield
- Anfield opened in 1884 with a capacity of about 20,000 and was originally the home of Everton FC
- A rent row saw the Toffees move to Goodison Park and the newly-formed Liverpool FC take up residence in 1892
- The famous Spion Kop opened in 1906, and a redesign in 1928 gave it a capacity of 30,000
- Anfield's highest attendance came in 1952, when 61,905 saw the Reds take on Wolverhampton Wanderers
- The introduction of seating on the Kop and redesigns of the Anfield Road, Kemlyn Road (Centenary) and Main stands brought the capacity to just over 45,000
Source: Liverpool FC