The highly-rated defender's performances caught the eye last season as Coventry finished runners-up to Spurs in the FA Women's Premier League. Spurs went on to win the national play-off against Blackburn to take their place in the Women's Super League next season.
It's the team's second signing in as many days after announcing the capture of top WSL2 striker Sarah Wiltshire.
"Ashleigh is certainly one of the best defenders we faced in the league last season," said manager Karen Hills.
"She's versatile, strong and attack-minded, she's alwways looking to push forward but she's a great defender as well, so she's really suited to our style of play.