At a Monday afternoon ceremony, Cooper said, "The lack of health care is an economic crisis. With this bill, more uninsured North Carolinians can avoid financial ruin from unpaid medical bills. More rural hospitals will be able to stay open. Businesses won't lose as many good workers to illness or to care for sick family."
State lawmakers gave their final approval last week in a vote 87 to 24 in favor of House Bill 76, also known as Access to Health Care Options.
"Medicaid expansion is a once-in-a-generation investment that will strengthen our mental health system, boost our rural hospitals, support working families and so much more," Cooper said. "This is a historic step toward a healthier North Carolina that will bring people the opportunity of better health and a better life."
WATCH: Cooper speaks before signing Medicaid expansion bill
Gov. Roy Cooper's remarks before signing Medicaid bill
This would direct state health officials to accept Medicaid for potentially 600,000 more low-income adults especially those living in rural areas.
In North Carolina, rural residents are 40% more likely to be uninsured and eligible for Medicaid expansion, and 11 rural hospitals have closed in North Carolina since 2005.
North Carolina, like other states, is dealing with an opioid and substance abuse crisis, Cooper's office said. "About 40% of overdose patients in emergency departments are uninsured, making it harder for them to get the follow-up mental health care they need.
But the expansion will not go into effect until the state budget is approved in the summer.
"It's only a question of when and not if," Cooper said, and he noted that the budget process is often complicated but felt sure an agreement would be reached.
I'm grateful for those who've spent years fighting for this," said Cooper, a Democrat. "Child welfare advocates, health care workers, veterans groups, hospitals, people of faith, Care 4 Carolina, and the nonprofit groups, businesses, sheriffs and local elected officials from both parties."
WATCH: Berger, Moore speak on Medicaid expansion process
GOP leaders talk about Medicaid expansion
Senate Leader Phil Berger, R-Rockingham also spoke at the ceremony.
Berger said he was glad the deal got done and done right.
"While this is a momentous occasion, our work is not done," Berger said.
House Speaker Tim Moore, R-Cleveland also thanked community members for their work and support.
"This has been a long day coming," Moore said. "But it's been one as a result of a lot of reforms."
WATCH: Senate Minority Leader Dan Blue's remarks on Medicaid deal
Senate Minority Leader Dan Blue on Medicaid
In a statement, NCDP Chair Anderson Clayton said: "Today is a great day in North Carolina as more than 600,000 working people across this state will finally have access to affordable health care. This is a win for everyone in the Tar Heel State - from rural hospitals fighting to keep their doors open to law enforcement combating the opioid epidemic, and advocates who have bravely told their story. We are all better off because of the bipartisan work it took to get this done, and I am grateful for everyone who has fought for 13 years to make this happen."
Medicaid advocates talk about impact of new law