The network originally picked up the pilot, created by Pulling star Sharon Horgan, late last month.
Deadline now reports that Elfman could play Julia, a woman whose two children have been raised by her own mother Marian. The series will follow Julia as she is forced to take responsibility when Marian decides to live her own life.
Elfman previously starred in ABC sitcom Dharma & Greg from 1997 to 2002 and has also featured in episodes of Brothers & Sisters and My Name Is Earl. Last year, she appeared in NBC comedy Accidentally On Purpose but the series was axed after a single season.
The Bad Mom pilot will be executive produced by Horgan and Aaron Kaplan, and is under consideration for ABC's 2011-12 television season.