The company was founded in 1928 by Ralph Bullock initially as a haulage firm, with milk deliveries being the early focus. At the weekend, the trucks turned into cloth-top charabancs for trips to the seaside. By the mid-1930s, the fleet included trucks and proper coaches, but the trucks were nationalised under the Transport Act 1947 by the Clement Attlee government, leaving only the coaches. Ralph was fond of Foden coaches, and the majority of the fleet throughout the 1940s to 1960s were Fodens, of which two still survive to this day, the oldest from 1949 is still roadworthy, and is currently on loan to the Museum of Transport in Manchester.
The firm remained small with around 20 vehicles, until 1986, when deregulation of the bus market allowed Bullocks to diversify. The fleet grew to around 75-80 vehicles in total with Bullocks acquiring many bus routes, and introducing new ones, including route 42 from Stockport to Manchester via Wilmslow Road. Over the years, the number of services declined having been lost to other operators. By 2008, it was operating seven routes and several school services, all except one of the commercial routes were sold off, most to Stagecoach Manchester and a couple to Arriva North West.
In August 2008 Stagecoach Manchester purchased all of the commercial bus operations of Bullocks except route 147. Bullocks continue to operate several school bus services, as well as coaches.