On November 11, 1929, while hiding in Dallas County from her husband, Blanche met Buck Barrow, a twice-divorced criminal with children from a previous marriage. Nevertheless, the couple fell in love.
On November 29, 1929, several days after meeting Blanche, Buck Barrow was shot and captured following a burglary in Denton, Texas. He was tried, convicted, and sentenced to five years in the Texas State Prison System. On March 8, 1930, however, Barrow escaped from the Ferguson Prison Farm near Midway, Texas. In interviews with author/historian John Neal Phillips, Blanche was frank about the fact that she not only knew of Buck's escape, but that she hid with him and actually staged robberies with him. The notion that Blanche did not know until later that Buck was an escaped convict was fabricated by the Barrow family and Blanche herself as a means of convincing Missouri State authorities to reduce her prison sentence following her capture in July 1933.
On July 3, 1931, Blanche and Buck were married in Oklahoma. They honeymooned in Florida. Despite hiding with her husband and accompanying him on a number of armed robberies, Blanche was not interested in pursuing a criminal career. She and other members of the Barrow family convinced Buck to turn himself in to Texas prison authorities and complete his sentence. On December 27, 1931, Buck was driven to Huntsville, Texas, where he walked up to the front gate and told startled prison officials that he had escaped almost two years before and needed to resume his sentence. Upon his release, March 22, 1933, Buck Barrow, in the company of Blanche, joined his younger brother Clyde, Bonnie Parker, and W. D. Jones in Joplin, Missouri, where he participated in several armed robberies.
Although Blanche Barrow never once fired a gun during this time, she was present during the April 13, 1933, shootout in Joplin, in which two law officers, Newton County Constable Wes Harryman and Joplin City Motor Detective Harry McGinnis, were killed. She was not present, however, when Buck and Jones killed Alma City Marshal Henry Humphrey during a brief shootout on the road between Alma and Fayetteville, Arkansas on June 23, 1933. But she was present during the July 19, 1933, gunfight at the Red Crown Tourist Court near Platte City, Missouri in which three people were wounded, including Platte County Sheriff Holt Coffey. Buck was severely wounded in the withering gunfire, shot through the head and Blanche took shards of glass in her eyes, but all five gang members escaped to an abandoned amusement park near Dexter, Iowa. On July 24, 1933, five days later, there was yet another battle when a posse and spectator contingent numbering over 100 converged on their campsite. Buck was wounded again, this time in the back, and was captured along with Blanche. Bonnie, Clyde, and W. D. Jones, all wounded, escaped on foot through the brush. Buck died at Kings Daughters Hospital in Perry, Iowa on July 29, 1933, of complications involving his wounds.