The 19-year-old dribbled into the left side of the box and curled in a long shot off the far, top corner of the goal frame to become Juventus' youngest scorer in his first match in Europe's top club competition.
The Turkey winger's 21st-minute goal set Juventus on the way to a 3-1 win over PSV Eindhoven on Tuesday while Aston Villa, returning to Europe's top table after a four-decades long absence, won 3-0 at Young Boys of Berne.
That was also fittingly appropriate given the club were mourning the death, a day earlier, of 1982 European Cup winner Gary Shaw.
At 19 years and 136 days Yildaz broke a record set by Alessandro Del Piero, who also wore No.10, when he scored at 20 years and 308 days against Borussia Dortmund in September 1995.
Further goals from Weston McKennien and Nico Gonzalez brought a debut Champions League victory for new Juventus coach Thiago Motta who led Bologna to qualification last season.
Youri Tielemans put Villa ahead with a bouncing shot midway through the first half and Jacob Ramsey doubled the lead 11 minutes later by taking advantage of a loose ball. Amadou Onana sealed it four minutes from time.
The only downside for Villa was an ankle injury that forced off England forward Ollie Watkins in the 60th minute.
Liverpool were due to play Milan in one of the later ties with the match overshadowed by the death, in a traffic accident in the early hours of Tuesday morning, of a 51-year-old fan.
Philip Joseph Dooley, from Liverpool, died after the accident in nearby Bergamo Merseyside Police said. He was in collision with a vehicle as he crossed a road.
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