She joins new club Loughborough Lightning with immediate effect.
Scarratt, 28, is among the first three players to be awarded a XVs contract, starting in 2019.
Natasha Hunt, 2014 World Cup winner, is also leaving the Sevens program to join Gloucester-Hartpury, while Jess Breach returns to Harlequins Ladies.
All three forfeit the chance to play at the Tokyo 2020 Olympic Games but will be considered for the next Women’s Rugby World Cup in 2021 in New Zealand.
They are each also now eligible to play in the Tyrrells Premier XVs – the top-tier of the women’s English rugby union domestic league.
Scarratt’s signature for Loughborough Lightning will be a coup for the club, currently third in the Premier XVs league.
She last played for Lichfield before focusing on Sevens, but the club failed in their bid to win a franchise to play in the Premier XVs.
Scarratt was also World Cup winner in 2014. She went on to be named the Rugby Union Writer’s Club Pat Marshall winner in 2015 after she scored 16 points in the Red Roses 21-9 final win over Canada in Paris.
The Rugby Football Union announced their Women’s 15-a-side players would be going professional in 2019 earlier this year.
A total of 28 full time XVs women’s contracts will be awarded, with the final 25 names announced on 3 January.
Meanwhile, 2014 World Cup finalist Amy Wilson-Hardy has rejoined the Sevens programme.