The Hollywood actor and comedian posted footage on Instagram showing the group of mothers holding up signs and speaking out at the hearing on Tuesday – before they were removed by troopers.
“I love these woman it’s always women,” she captioned the post.
“Tennessee House subcommittee members had state troopers physically remove gun safety activists who quietly held signs from a hearing.”
She added: “We bow down to this woman who – visibly shaking – said: ‘You will have to drag me out.’ Moms will win.”
Several other celebrities also showed their support for the parents, with comedians Ilana Glazer and Sarah Silverman liking Schumber’s post.
On Tuesday, the bereaved family members were seen breaking down in tears as troopers from the Tennessee Highway Patrol removed them from the second day of the legislative session where they'd been called to testify about gun control.
"I was supposed to speak, I was supposed to testify," said Sarah Shoop Neumann, sobbing and shaking in front of the silent GOP-controlled House subcommittee room.
Ms Neumann is a parent whose child attends The Covenant School — a private Christian grade school where three children and three staff were killed in a mass shooting in March. The suspect, 28-year-old Audrey Hale, was killed after being confronted and killed by police.
Ms Neumann said she was later allowed back to testify against a bill that allows for more teachers to carry guns at school. The House subcommittee advanced the bill, though its odds appear longer in the Senate.
"We're just trying to do something," Ms Neumann later told reporters, as other Covenant parents huddled around her. "It's overwhelming."
Republican governor Bill Lee had initially called lawmakers back to the Capitol to consider his proposal to keep firearms away from dangerous people. But his bill was defeated by the Republican supermajority, where legislative leaders have largely refused to consider the issue.
Without any debate, three variations of similar proposals for so-called extreme risk protection orders, or ERPOs, carried by Democratic rep Bob Freeman of Nashville, immediately failed Tuesday in the same House subcommittee where the public was kicked out.
On the first day of the special session on Monday, House Republicans advanced a new set of procedural rules that carried harsh penalties for lawmakers deemed too disruptive or distracting, and banned visitors from carrying signs inside the Capitol and in legislative hearing rooms.
The Senate and House also signed off on severely limiting the public from accessing the galleries where people have traditionally been allowed to watch their government in action.
Protesters on Tuesday defied the new sign ban by showing up to the House chamber with pro-gun control messages written on their bodies and clothes. Others wrote out messages on their phones and held them up for lawmakers to see.
That defiance faced a harsher response as lawmakers broke out into committee rooms to begin debating legislation.
Allison Polidor, a gun control advocate from Nashville, was escorted out of a hearing room because she was holding a sign that said, "1 KID > ALL THE GUNS."
"I wasn't saying anything. I wasn't doing anything. I was holding up a sign," Ms Polidor said.
Republican state representative Lowell Russell, who oversaw the meeting, had also warned that he could order everyone out of the room.
Shortly after, another Republican lawmaker said his bill was stalled that would let people with handgun carry permits bring guns onto K-12 and college school property if they know the school doesn't have armed security. That announcement sparked some gun control advocates in the crowd to break out in applause.
"Are we going to quiet down and listen, or are we going to sit there and clap?" Mr Russell said.
When some kept clapping, Russell said, "Alright, troopers, let's go ahead and clear the room." Members of the media were allowed to stay, and some members of the public who were testifying on legislation were allowed in.
"We gave them three or four times to not do outbursts in the committee hearing, and unfortunately they continued after three, maybe four warnings," Mr Russell told The Associated Press afterward. "So unfortunately, that's just the way it goes, if they don't follow the rules."
Additional reporting by agencies