People who assault emergency services workers face tougher sentences now the maximum jail term has been increased from six to 12 months.
The Assaults on Emergency Workers (Offences) Act covers attacks on 999 staff and other blue light volunteers.
There are about 20 assaults on emergency staff in Wales every day, according to Rhondda MP Chris Bryant who tabled the private members' bill.
North Wales Police has recorded 200 assaults on staff since April.
These have ranged from being spat at to having a broken jaw, the force's Temporary Assistant Chief Constable Neill Anderson said.
The new law makes attacks on emergency workers an aggravating feature in terms of sentencing, and introduces a new offence for minor assaults against them.
It builds on the previous offence of assaulting a police officer, and also provides extra protection to unpaid volunteers who support the emergency services, including mountain rescuers and RNLI crews.
An average of nine South Wales Police officers are assaulted each week, the force said.
Chief Constable Matt Jukes added: "Staff do not go to work to be assaulted or threatened.
"Police officers and staff are people, and committed public servants - not punchbags."
Stuart Millington, senior operations manager for North Wales Fire and Rescue Service, said workers "should not be subject to abuse of any nature".
And Louie Platt, director of operations at Welsh Ambulance Service NHS Trust, said "violence not only puts our people at risk, but prevents them from doing their job".