The 27-year-old will join the Reds after spending eight years with Reading FC Women, which followed on from several years at Chelsea Women.
The full-back played more than 100 games for the Royals and will add a wealth of experience to the Reds’ backline.
LFC Women manager Vicky Jepson said: “Becky is the first signing of the summer and I’m delighted to welcome her to the club.
“She’s a reliable Women’s Super League player who’s been loyal to Reading for many years and will bring a lot of experience to our club.
“She’s a quick attacking full-back, which is something we need in our squad, so she will certainly add quality and I can’t wait to get started with her.