The 18-year-old who reached the junior boys final of all four grand slam tournaments this year, winning at Wimbledon and the U.S. Open, got the confirmation Tuesday when the International Tennis Federation announced its champions for 2012.
Novak Djokovic and Serena Williams were named world champions while Peliwo and American Taylor Townsend took the junior titles. Djokovic won the men's award for the second straight year, while Williams took the honour for the third time in her career.
Peliwo, the first player to reach all four grand slam finals in 28 years, is the first Canadian to hold two grand slam singles titles.
"I expected it to happen after I finished the U.S. Open (in September)," Peliwo said at the national team training centre. "It feels great just to be finally recognized officially as the world No. 1 junior."
He lost the Australian Open final to Luke Saville and the French Open final to Kimmer Coppejans, then beat Saville to take Wimbledon and Liam Broady to win the U.S. title.
He said consistency was the biggest factor in his final year of junior tennis.
"I managed to be able to bring my game up in the big tournaments and the grand slams, even when I wasn't playing my best," said Peliwo. "I found ways to win matches I was down in.
"Everything came together, whether it was my game, my mental strength, my consistency, the physical part. Hopefully I'll be able to keep that going."
His victory at Wimbledon came a day after Genie Bouchard of Westmount, Que., made history as the first Canadian grand slam singles winner when she took the junior girls title. Bouchard also took the junior doubles crown.
They were part of an unprecedented surge in Canadian tennis that saw power-hitting Milos Raonic rise to 13th in men's world rankings and the Davis Cup team maintain its place in the prestigious World Group for 2013.
Veteran Daniel Nestor of Toronto, the only other Canadian ITF world champion, has won eight grand slam doubles titles.
Peliwo will be at the sold-out Thunderbird Sports Centre in Vancouver when Canada faces Spain in Davis Cup first-round action Feb. 1-3, but only as a practice partner for Raonic, Nestor, 125th-ranked Vasek Pospisil and the rest of the squad.
"I'll hit with the guys, take in the experience," he said. "If it happens, I'm hoping maybe to play a dead rubber (a meaningless game when a best-of-five series is already decided). You never know. I'm not expecting it, but it would be a great experience."
Peliwo is beginning his own climb up the world rankings. He lost to Pospisil in the semifinals of a small event in Rimouski, Que., in March, but only turned pro for good after the U.S. Open.
Since then he had another semifinal appearance in Winnipeg, and made a first pro final Nov. 18 at an ITF Futures tournament in Mexico, losing to 18-year-old Frenchman Lucas Pouille.
"I ended up losing to someone I know pretty well from juniors, so that was a bit disappointing,'' he said. ''I beat him earlier this year, but I didn't play as well as I'd hoped.
"It was great to get past that semifinal barrier. I'm worming my way up there."
Peliwo is ranked 522nd and his goal for 2013 is to reach the top 250 or better.
"I'll work on developing my weapons while still playing really solid, like the top guys," he said. "The top guys don't usually blow people off the court.
"They just wear them out completely with their consistency and by moving them around."
Peliwo plans to spend the holidays with his family in Vancouver, then head to Florida in January for three Futures tournaments ahead of the Davis Cup.
Djokovic won the Australian Open and was runner-up at the French Open and U.S. Open. He finished the season No. 1 in the ATP rankings with six tour titles.
Williams won Wimbledon, the U.S. Open and the Olympic gold medal. She had a tour-best 58-4 record and seven titles.
American twins Bob and Mike Bryan were named men's doubles world champions for the ninth time in 10 years, while Sara Errani and Roberta Vinci of Italy took the women's doubles award.
Esther Vergeer of Netherlands won the women's wheelchair tennis award for the 13th consecutive year and Stephane Houde of France was named the men's winner.
— With files from The Associated Press.