Barcelona sign Walsh from Man City for world record fee
The previous world record women's transfer stood at a fee in excess of 250,000 pounds, which Chelsea had paid in 2020 to sign Denmark's Pernille Harder from VfL Wolfsburg.
Walsh who joined City in 2014 as a teenager and played 211 matches in all competitions for them, lifted eight trophies with the club in as many years.
She was in the final year of her contract at City, who had reportedly rejected previous bids from Spanish champions Barca.
A versatile player who can operate as a playmaker or defensive midfielder, Walsh was part of the England side that captured the woman's European Championship this year and was part of the team of the tournament.
"Everybody at Manchester City would like to thank Keira for her contributions during her time at the club and wish her all the best for the future," City said in a statement.
England internationals Lucy Bronze and Georgia Stanway as well as Scotland's Caroline Weir have all left City in recent months while Karen Bardsley, Ellen White and Jill Scott have retired.
City were third in the 2021-22 WSL season behind champions Chelsea and second-placed Arsenal. Barcelona won the Spanish league last season and were runners-up in the Champions League.