Hal Roach was born in 1892 in Elmira, New York. After working as a mule skinner, wrangler and gold prospector, among other things, he wound up in Hollywood and began picking up jobs as an extra in comedies, where he met comedian Harold Lloyd in 1913 in San Diego. By all accounts, including his own, he was a terrible actor, but he saw a future in the movie business and in Harold Lloyd. Roach came into a small inheritance and began producing, directing and writing a series of short film comedies, under the banner of Phun Philms (soon changed to Rolin, which lasted until 1922), starring Lloyd in early 1915. Initially these were abysmal, but with tremendous effort, the quality improved enough to be nominally financed and distributed by Pathe, which purchased Roach's product by the exposed foot of film. The Roach/Lloyd team morphed through two characters. The first, nominally tagged as "Will E. Work", proved hopeless; the second, "Lonesome Luke," an unabashed imitation of Charles Chaplin, proved more successful with each new release. Lloyd's increasing dissatisfaction with the Chaplin clone character irritated Roach to no end, and the two men engaged in a series of battles, walkouts and reconciliations. Ultimately Lloyd abandoned the character completely in 1917, creating his now-famous "Glasses" character, which met with even greater box-office success, much to the relief of Roach and Pathe. This new character hit a nerve with the post-war public as both the antithesis and complement to Chaplin, capturing the can-do optimism of the age. This enabled Roach to renegotiate the deal with Pathe and start his own production company, putting his little studio on a firm financial foundation. Hal Roach Productions became a unique entity in Hollywood. It operated as a sort of paternalistic boutique studio, releasing a surprising number of wildly popular shorts series and a handful of features. Quality was seldom compromised and his employees were treated as his most valuable asset.

Roach's relationship with his biggest earner was increasingly acrimonious after 1920 (among other things, Lloyd would bristle at Roach's demands to appear at the studio daily regardless of his production schedule). After achieving enormous success with features (interestingly, his only real feature flop of the 1930s was with General Spanky (1936), a very poorly conceived vehicle for the property), Lloyd had achieved superstar status by the standards of "The Roaring Twenties" and wanted his independence. The two men severed ties, with Roach retaining re-issue rights for Lloyd's shorts for the remainder of the decade. While both men built their careers together, it was Lloyd who first recognized his need for creative freedom, no longer needing Roach's financial support. This realization irked Roach, and from this point forward he found it difficult, if not impossible, to offer unadulterated praise for his former friend and star (while Lloyd himself was far more generous in his later praise of Roach, he, too, could be critical, if more accurate, in his recollections). Lloyd went on to much greater financial success at Paramount.

Despite facing the prospect of losing his biggest earner, Roach was already preoccupied with building his kiddie comedy series, Our Gang, which became an immediate hit with the public. By the time he turned 25 in 1917, Roach was wealthy and increasingly spending time away from his studio. He traveled extensively across Europe. By the early 1920s he had eclipsed Mack Sennett as the "King of Comedy" and created many of the most memorable comic series of all time. These included the team of Stan Laurel and Oliver Hardy, Charley Chase, Edgar Kennedy, 'Snub' Pollard and especially the long-running Our Gang series (AKA "The Little Rascals" in TV distribution). Pathe, which distributed his films, shut down its U.S. operations after its domestic representative, Paul Brunet, returned to France in 1927. But Roach was able to secure an even better deal with MGM (his key competitor, Mack Sennett, was also distributed by Pathe, but he was unable to land a deal, ultimately declaring bankruptcy in 1933). For the next eleven years Roach shored up MGM's bottom line, although the deal was probably more beneficial to Roach. In the mid-'30s Roach became inexplicably enamored of 'Benito Mussolini', and sought to secure a business alliance with the fascist dictator's recently completed film complex, Cinecitta. After Roach asked for (and received) assurances from Mussolini that Italy wasn't about to seek sanctions against the Jews, the two men formed RAM ("Roach And Mussolini") Productions, a move that appalled the powers at MGM parent company, Leow's Inc. These events coincided with Roach selling off "Our Gang" to MGM and committing himself solely to feature film production. In September 1937, Il Duce's son, Vittorio Mussolini, visited Hollywood and Roach's studio threw a lavish party celebrating his 21st birthday. Soon afterward the Italian government took on an increasingly anti-Semitic stance and, in retribution, Leow's chairman Nicholas Schenck canceled his distribution deal. Roach signed an adequate deal with United Artists in May 1938 and redeemed his previous record of feature misfires with a string of big hits: Topper (1937) (and its lesser sequels), the prestigious Of Mice and Men (1939) and, most significantly, One Million B.C. (1940), which became the most profitable movie of the year. Despite the nearly unanimous condemnation by his industry peers, Roach stubbornly refused to re-examine his attitudes over his dealings with Mussolini, even in the aftermath of World War II (he proudly displayed an autographed portrait of the dictator in his home up until his death). His tried-and-true formula for success was tested by audience demands for longer feature-length productions, and by the early 1940s he was forced to try his hand at making low-budget, full-length screwball comedies, musicals and dramas, although he still kept turning out extended two-reel-plus comedies, which he tagged as "streamliners"; they failed to catch on with post-war audiences. By the 1950s he was producing mainly for television (My Little Margie (1952), Blondie (1957) and The Gale Storm Show: Oh! Susanna (1956), for example). His willingness to delve into TV production flew in the face of most of the major Hollywood studios of the day. He made a stab at retirement but his son, Hal Roach Jr., proved an inept businessman and drove the studio to the brink of bankruptcy by 1959. Roach returned and focused on facilities leasing and managing the TV rights of his film catalog.

In 1983 his company developed the first successful digital colorization process. Roach then became a producer for many TV series on the Disney Channel, and his company still produces most of their films and videos. He died peacefully just shy of his 101st birthday, telling stories right up until the end.