The loss dropped the Tigers (16-6, 5-4 Southeastern Conference) to 0-5 in true road games. They have won three games at neutral sites this season.
Laurence Bowers was wide open when he hit a 3-pointer to give Missouri its first lead of the game, 68-67, with 53 seconds left.
Harris turned it over on Texas A&M's next possession, but Phil Pressey gave it right back with a turnover to set up the winning score for A&M (14-8, 4-5).
Ray Turner blocked a shot by Keion Bell with 2 seconds left to secure the win.
Alex Oriakhi led the Tigers with 15 points.
COLUMBIA, Mo. (AP) - The University of Missouri's first year in the Southeastern Conference continues to pay dividends away from the field.
School officials on Tuesday announced an $8.3 million gift from Don and Audrey Walsworth of Marceline. The donation follows a $30 million gift from the Kansas City Sports Trust in June and a $6.4 million anonymous contribution in December.
The Walsworth gift will go toward previously announced Memorial Stadium improvements. The school plans to add 6,000 seats to the stadium, which now holds 71,004 fans.
Missouri will also build a new clubhouse for the men's and women's golf teams at a private course in Columbia used by the school.
Walsworth is the CEO of a northern Missouri publishing company and a former chairman of the university's Board of Curators.