The team announced the deals Saturday. Gaine signed a five-year contract and O'Brien was extended for four years.
Gaine brings 19 years of NFL personnel experience to Houston. He spent the 2017 season as the Buffalo Bills' vice president of player personnel. He also served as the Texans' director of player personnel from 2015-16 and director of pro personnel in 2014.
Texans owner Bob McNair calls Gaine an "incredibly smart, hardworking individual that understands the importance of good communication."
Houston finished 4-12 this season after consecutive AFC South titles the previous two years. O'Brien's 31 career victories in four years are tied for the most by a coach in franchise history.
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