Lallana is set to leave Liverpool when his contract expires at the end of the current campaign.
With the season delayed until June 17 due to the coronavirus, Lallana would have been out of contract before the campaign concludes.
Now the 32-year-old England midfielder will be able to celebrate with the rest of the Liverpool squad once they clinch the Premier League crown.
Jurgen Klopp’s side need a maximum of two wins from their last nine games to win the club’s first English title since 1990.
“I am really pleased to have the chance to finish this season – it means a lot to me and my family,” Lallana told Liverpool’s website on Tuesday.
“Of course, one of the big personal positives about committing to this short-term extension is that I will now get to say goodbye to the people who mean so much to me in the right way.
“I’m buzzing to be seeing out this campaign and hopefully get to celebrate something memorable with an amazing group of people.”
Lallana is a popular and influential figure in the Liverpool squad and Reds boss Klopp paid tribute to his contribution despite recurring injury problems in recent seasons.
“This is absolutely how it should be, too, because I am so pleased he will be with us to finish the job this season and have the farewell he deserves so much,” Klopp said.
“It is not possible for me to find words in the English language to properly explain the importance of Adam Lallana during my period of being manager of this club.”
Lallana has been strongly linked with a move to Leicester, whose manager Brendan Rodgers brought him to Anfield from Southampton in 2014.
Lallana has played 15 league games and scored once this term as Liverpool stormed 25 points clear before the season was halted by the pandemic.
“I know how highly sought after Adam is in this moment by other clubs who want him for next season, so for him this is a commitment to us and we are very appreciative to him for it,” Klopp said.
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