The comedy drama, which also stars Ben Lawson, focuses on two very different lawyers who look after people misbehaving on nights out in Las Vegas.
Finnigan has now signed up for the female lead, Deadline reports.
She will play one of the lawyers on the show, Eliza Evans, while Lawson will appear as attorney Will Garratt.
Finnigan recently played Maddie in the ABC comedy Better With You, but the show was dropped after one season. She has also starred in series including The Bold and the Beautiful and Crossing Jordan.
As well as Wild Card, USA is also developing a remake of the British comedy Sirens, a drama called Over/Under, the Michael Ealy project Common Law and con artist series Eden.