The 24-year-old has signed a one-year deal at the club, and becomes the third women’s team signing of the summer following the arrivals of Danique Kerkdijk and Matilde Skovsen.
Women’s first-team manager Hope Powell said, “We are delighted to welcome someone of Megan’s experience to the club.
“She has a proven knowledge of playing at the highest level, and will bolster our options in the goalkeeping positions following the departures of Marie [Hourihan] and Lucy [Gillett].
“I am very much looking forward to working with Megan, and wish her every success during her time at the club.”
Walsh began her career at Aston Villa before she joined Everton in 2013, and made the step up to FA Women’s Super League football.
Following two years on Merseyside, the shot-stopper had a spell at Notts County in 2015, before agreeing to join Yeovil for the 2017 FA WSL Spring Series, in a deal that would be extended following County’s liquidation.
The keeper has also represented Great Britain at the 2017 University Games, and featured for England up to under-23 level.