Ontario is a city located in San Bernardino County, California, United States. As of the 2000 Census, the city had a total population of 158,007. It is the home of LA/Ontario International Airport and the huge Ontario Mills shopping mall. It is also the former home of the Ontario Motor Speedway. It takes its name from the Ontario Model Colony development established in 1882 by Canadian engineers George Chaffey and William Chaffey, who named the settlement after their home province of Ontario, Canada. Ontario apartments for rent comparison page shows most up to date rent information on Ontario apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.