Illinois (8-0) took charge behind Bertrand, who also scored on a drives in the decisive surge to lift the Illini from a 58-54 deficit late in the second half.
The Illini finished the game on a 21-4 run.
Bertrand, a redshirt junior, scored 12 of his 15 points in the second half. Brandon Paul also scored 15 points for the Illini while forward Tyler Griffey and guard D.J. Richardson had 14 points apiece.
Kammeon Holsey led Georgia Tech (4-2) with 14 points while Jason Morris and Mfon Udofia scored 10 points apiece. The Yellow Jackets appeared to grab control with a 12-3 run midway through the second half for a 54-50 lead.
Illinois entered the week as the nation's leading 3-point shooting team, making an average of 10.9 per game. The Illini quickly found themselves in a long-distance shooting contest with Georgia Tech.
The teams combined to make 6 of 10 from beyond the 3-point line to start the game. But the Illini kept up the heat, finishing with a season-high 14 3-pointers, one short of the Assembly Hall game record.
Meanwhile, the Illini used a 2/3 zone defense for long stretches, something not seen from Illinois in Assembly Hall in years. After losing 12 of its last 14 games last season, Illinois is off to a hot start under first-year coach John Groce. He became the only coach since World War II to start his Illini career with eight wins. Illinois has 31-game non-conference winning streak in regular season games in Assembly Hall. A loss to Dayton in 2011, when Georgia Tech's Brian Gregory was coaching the Flyers, came in the NIT.
Illinois, which relied upon 3-point shooting in its biggest wins this season, used 3-pointers from Richardson and Griffey in an 8-2 run to start the second half for a 44-37 lead.
But Georgia Tech rallied with two 3-pointers from Chris Bolden and a breakaway dunk by Morris for a 54-50 lead with 10:16 left.
Georgia Tech was finishing an eight-day trip. After placing third in the DirecTV Classic in Anaheim, Calif., the Yellow Jackets made seven of their first 10 shots to grab a 21-15 lead.
The lead changed hands six times in a back-and-forth battle in the first half, when Illinois shot 46.7 percent from the 3-point line while the Yellow Jackets hit 45.5 from behind the arc.