The 18-year-old from Vancouver beat Australia's Luke Saville 7-5, 6-4 on Sunday to win the boys' crown, a day after fellow Canuck Eugenie Bouchard won the girls' trophy.
The Westmount, Que., native also added the girls' doubles crown on Sunday as she and Taylor Townsend of the U.S. defeated Switzerland's Belinda Bencic and Croatia's Ana Konjuh 6-4, 6-3.
The wins gave Canada an unprecedented three titles at a Grand Slam event. Bouchard's victory in the girls' final on Saturday marked the first time a Canadian has won a singles final at any level at a major.
Peliwo, who lost to Saville in the Australian Open boys' final in January, said he used Bouchard's victory in singles as inspiration.
"I wasn't jealous of her title, but it made me ever more hungry, I wanted to have the same feeling for myself and for Canada. I knew it would be a great achievement if we were both champions," said Peliwo, who also lost in the boys' final at the French Open. "The two previous finals that I lost were also a big inspirations, I didn't want to lose again but (I) was not letting it get to my head."
Peliwo recovered to win both sets against Saville, coming from 2-5 down in the opener in a match that started 90 minutes late due to rain and was played at the same time as Bouchard was on another court at the All England Club.
"Guys know that I fight no matter how far down I am, it's worked for me in many situations," he said. "Even if I don't believe I will win, I give it my absolute best and try to win every point, one point at a time.
"I can only go give my best and hope for a win."
Peliwo won the first set in 51 minutes, then fought back in the second while trailing Saville 3-1. The Canadian won five of the last six games, clinching the trophy with his fifth ace.
"That's exactly how I wanted to finish it," said Peliwo. "I was happy I battled back in the first set, gave myself a winning chance and took it on my first match point."
Peliwo finished with 19 winners, 14 unforced errors and converted on four of 11 break chances in 92 minutes.
Bouchard's second junior Grand Slam title-winning effort lasted 72 minutes and was paused by rain for 10 minutes in the opening set.
The 18-year-old, ranked 309 on the WTA list, lead her team to four breaks of serve from 12 chances, with the Canadian-American pairing saving the only break point they faced.
Bouchard's top-seeded team broke to start the match and claimed the opening set in 32 minutes. They came back from an early break in the second to claim the title on a second match point.
Canadian tennis ace Milos Raonic took to Twitter to congratulate both Peliwo and Bouchard.
"Big congrats to two amazing Canadian talents and athletes with great futures. These two owned Wimby juniors!!" tweeted Raonic, the 22nd ranked men's singles player in the world.
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