Those who buy from breeders and sell to pet stores must also get a license.
Ohio has had a reputation of being soft on oversight of large dog breeding operations.
The legislation regulating puppy mills has been seven years in the making and was approved more than a year ago, The Columbus Dispatch reported.
But because rules about care, caging and other standards had to go through a legislative process, the Ohio Department of Agriculture set the licensing deadline for Jan. 1.
How many breeders will be licensed isn’t known yet.
About 300 people have identified themselves as high-volume breeders in a survey, said Erica Hawkins, a spokeswoman for the department of agriculture
The department has about 100 license applications in progress and has completed 13, she said.
The law sets standards for housing and care of puppies and dogs. Those include making sure kennels are clean, properly ventilated and have temperature controls.
It also regulates how much space the dogs have and requires shelter from weather.
Background checks and insurance also will be required for breeders. They also must have a relationship with a veterinarian who can provide care for the animals.
The department of agriculture has hired four inspectors, a supervisor and staff to oversee the program, Hawkins said.
It also opened an office in Millersburg in Holmes County, which is home to many dog breeders.
The Ohio Association of Animal Owners backed the law as it was debated in the legislature and said it long believed dog breeding should be overseen by the state’s agriculture department.