The 32-year-old former runner-up was staring at a second successive grand slam defeat to the 18-year-old tyro when he trailed 5-2 in the decider but as Shapovalov's youth betrayed him for the first time, Tsonga roared back to rattle off the last four games for a 3-6 6-3 1-6 7-6(4) 7-5 victory.
"I'm tired but really happy," the popular Frenchman, who has been troubled by a calf injury in the build-up to the tournament, said on Margaret Court Arena.
"I did a big fight today. It's not easy to play the young guns, they play great and go for everything so it's difficult to defend. I suffered physically but I continued to fight."
Melbourne debutant Shapovalov, who won in straight sets in their US Open second round clash, crunched 60 winners throughout the three hour 37 minute firefight in soaring temperatures, but ultimately fell just short.
The straggly-haired world number 50's explosive shot-making helped him take the opener in style after breaking the 15th seed's serve in the fourth game of the match.
Tsonga, popular Down Under after his final appearance against Novak Djokovic 10 years ago, found some extra zip on his shots to level the match but the fearless Shapovalov continued to let rip at every opportunity to race through the third set in 26 minutes.
It was tight in the fourth as 32-year-old former world number five Tsonga used all his experience and physical presence to stay ahead on serve and take the teenager into a tiebreak which he dominated to win 7-4.
Shapovalov had only gone to a fifth set once before but broke in the second game and even had a chance to make it 4-0.
Tsonga dug in though and it was Shapovalov who crumbled when serving for the match at 5-3, misfiring two backhands and double-faulting to allow Tsonga to break.
The momentum was now with the older man and he played three faultless games to claim a 16th five-set victory and set up a possible clash with home favourite Nick Kyrgios who was due to play his second round later.
