The St. Louis Circuit Court ordered Pure Air to pay $35,000 in fines.
The lawsuit is the first case of its kind in Missouri.
Attorney General Chris Koster sued the company after his office received more than 1,100 complaints against Pure Air, Inc.
Koster said Pure Air made tens of thousands of "robo-calls" to Missouri residents registered on the state's Do Not Call list.
The calls continued even after many consumers asked the company to stop calling them.
Koster said in at least one case, a company representative told a consumer that it did not have to follow Missouri's No Call law.
"In 2013, more Missourians complained to my office about Pure Air than any other single telemarketer," said Koster. "We will continue to aggressively protect consumers against telemarketers who violate our consumer laws."
The Do Not Call list protects consumers from unwanted telemarketing calls.
Once a number is registered, businesses are legally prohibited from making unsolicited calls to your phone.
Missourians can get their number on the list by calling 866-NO-CALL (866-662-2551).