The show, which premiered last summer and returned to the schedule this week, features a biracial lesbian couple with a household of foster children.
One Million Moms, affiliated with the conservative American Family Association, urged its followers to contact ABC Family last fall to stop the show when it was a pilot and the network had yet to pick it up. The group has said it objects to the show's redefining of marriage and family.
"A stamp of disapproval from One Million Moms is like a critic's pick," said Peter Paige, executive producer of the show along with Jennifer Lopez, on Friday. "I'm incredibly grateful for their attention."
Teri Polo, who plays one of the moms, said the criticism contributed to "The Fosters" getting more attention when it started than it otherwise might have.
The show attracted 1.9 million people on Monday and was cable's top show among females aged 12 to 34, its target audience, the Nielsen company said. The show gained in viewership throughout last summer, a strong sign for a new show, and has already been renewed for another season.
On its website, One Million Moms said that foster care and adoption is "a wonderful thing, and the Bible does teach us to help orphans. This program is attempting to redefine marriage and family by having these two moms raise these children together." Attempts to reach a representative for the group on Friday were not immediately successful.
Paige said he had received a tweet of approval from Rosie O'Donnell, who said that she binge-watched several episodes of "The Fosters" with her daughter and asked if she could appear on the show. Paige took her up on the offer.