Seat belt use is already mandatory. But the new law makes it a primary offense, meaning a driver would not have to be stopped for another violation first. The bill passed the Senate on a 24-10 vote Wednesday after contentious debate in the House and narrow passage two weeks ago.
The fine for failing to wear a seat belt would be $25, with no court costs or points on a driver's license.
The state police and other supporters say the bill will increase seat belt use and save lives.
Opponents have said seat belt use is a matter of personal responsibility and freedom.