The new deal keeps the Irish defender at the Club until the end of the 2020/21 season.
The full-back expressed her excitement at extending her time with Blues and is looking ahead with eagerness for the new campaign.
Scott said: “I’m excited for next season and, personally, I’ve really enjoyed being in this environment with top level players.
“It’s a great place to be.”
The 26-year-old left Reading at the end of the 2017/18 season to join Blues after 16 years with the Berkshire side.
Scott made 14 appearances during her first season at Blues.
The aggressive full-back with excellent technical attributes has slotted in well at Blues and will be pushing to establish herself as an ever present in the team.
Blues Manager Marta Tejedor commented: "Harriet is a very experienced player who can play in different positions and take different roles inside the team.
"She is a very hard working player who perfectly suits our values as a club: effort, commitment, personal growth. She's a player with no limits who can go on to achieve high levels of excellence in what is proposed."
Off the pitch, Scott has been juggling football with her studies, showing her determined and tenacious nature.