Fultz had 13 points, 10 rebounds and 10 assists in 25 minutes off the bench as the Sixers won their 16th straight game, 130-95, over the Milwaukee Bucks.
At 19 years and 317 days, Fultz is the first teenager to post a triple-double, bestingLos Angeles LakersrookieLonzo Ball (20 years, 15 days), who earlier this season took over the distinction from Cleveland Cavaliers star LeBron James (20 years, 20 days).
Fultz's landmark night provided an uplifting finish to a regular season that was marred by a lengthy absence because of a shoulder injury that kept him out of the lineup for 68 games.
"To see his teammates react to Markelle Fultz was special," 76ers coach Brett Brown said. "I think it's a snapshot into who these guys are."
Fultz, the No. 1 overall pick in the 2017 draft, averaged 7.1 points, 3.1 rebounds and 3.8 assists during the regular season.
In their first playoff appearance since the 2011-12 season, the third-seeded Sixers will face the No. 6 seed Miami Heat.
Fultz, 76ers make history in final regular season game
Markelle Fultz becomes the youngest player to notch a triple-double in NBA history and leads the 76ers to a franchise-record 16th straight win.
Do you 'Trust the Process' now?
The 76ers charge into the playoffs for the first time since 2012 on a 16-game win streak behind superstar play from Ben Simmons and Joel Embiid and ready to make some noise.