After nine years in the Denver area, the Millers returned to Salt Lake City when Larry formed a partnership with William Reid Horne to purchase a Toyota dealership in Murray. It opened on 1 May 1979 as Larry H. Miller Toyota. In October 1981 Miller bought out his uncle's share in the business. Throughout the 1980s and early 1990s he acquired a number of automobile dealerships in Utah, Colorado, Arizona, and New Mexico. In 1993 Automotive Age listed him as the fifteenth largest U.S. car dealer, with nineteen dealerships.

Larry H. Miller became a co-owner of the Utah Jazz professional basketball team when he purchased a half interest in the team on 11 April 1985 for $8 million. Just over a year later, in order to prevent the sale and subsequent move of the Utah Jazz to Minnesota, on 16 June 1986 he bought the remaining fifty-percent interest from Sam Battistone for $14 million.

Under Miller's leadership and his private financing, ground was broken on 22 May 1990 for a new $66 million arena. Named the Delta Center, the state-of-the-art arena was completed on budget and on schedule on 4 October 1991. His success in managing the Delta Center project led Salt Lake City Mayor Deedee Corradini to ask Larry to serve without pay as the building project manager for the new baseball field, the Franklin Quest Baseball Field, constructed between 1993 and 1994. Miller also purchased the Salt Lake Golden Eagles Hockey Team in September 1989 and television station KXIV, which he renamed KJZZ in 1993.