M. MacIntyre was born Marjorie Phyllis Hull on November 6, 1904 in Belleville, New Jersey. She was raised by her mother and her grandparents at 194 North 16th Street in East Orange, NJ. In 1926 Marjorie Phyllis Hull married David William MacIntyre. By 1930 her husband had left home and the marriage had ended unhappily in divorce. Marjorie MacIntyre raised her son as a single parent in East Orange.
In May of 1936 Marjorie MacIntyre wrote, drew, lettered, and inked two features, "Ko Ko" and "Whiskers" that appeared in The Comics Magazine, one of America's first comic books that featured original material, rather than reprinted newspaper comic strips. Her work later appeared in Funny Pages, and The Funny Picture Story Magazine. She signed her work for comic books as "M. MacIntyre" to disguise her gender in a male-dominant industry.
Marjorie Phyllis Hull MacIntyre Johnson died at the age of ninety in Illinois on July 17, 1995.