The Reds confirmed the news on their official website on Wednesday, saying that the 25-year-old would now travel to Merseyside to undergo a medical and discuss personal terms.
Liverpool had previously had two bids rejected in the January transfer window for Adam, with the highest offer reported to be in the region of £6.5 million.
This time, however, it is understood that Blackpool have accepted £7.5 million rising to £8 million depending on appearances.
The Seasiders had wanted to keep Adam in January to aid their battle against the drop.
However, that battle proved unsuccessful, and Blackpool turned their focus to achieving maximum value for a player who had just one year remaining on his contract.
Adam is a Scottish international who was shortlisted for the Premier League Player of the Year award last season after scoring twelve goals in 35 league appearances.
The former Rangers player becomes Liverpool's second summer signing, following the capture of young England midfielder Jordan Henderson from Sunderland last month for a fee reported to be in the region of £20 million.
The Anfield club failed with a £15 million bid for Aston Villa winger Stewart Downing on Tuesday, but the agent of Roma's Brazilian goalkeeper Alexander Doni has claimed that his client is close to sealing a move to Merseyside.
In addition, England full-back Glen Johnson has signed a contract extension, although the length of the new deal was not disclosed.