The six-part series, which will air on the Sundance Channel in the US, has been written by The Piano's Jane Campion.
It is set in New Zealand's mountains and follows what happens when a pregnant 12-year-old girl seen standing in a frozen lake goes missing.
Mad Men's Elisabeth Moss has already signed up to play Robin Griffin, the detective leading the search for the missing girl.
Lawless has now also joined the cast, TV Line reports.
Lawless has previously starred in shows such as Xena: Warrior Princess, Battlestar Galactica and Spartacus.
Holly Hunter, Peter Mullan and David Wenham are among the other actors who have signed up for roles in Top of the Lake.