Shelton blasted an ace on match point to seal the win and avenge his five-set loss to Tiafoe at last year's U.S. Open as the 22-year-old continues to make strides in his breakout season.
The opening Grand Slam of the year begins at Melbourne Park on Sunday.
Novak Djokovic's quest for a record Grand Slam title continued in dramatic circumstances after fifth seed Lorenzo Musetti quit their Australian Open quarter-final match with an injury after taking a two-set lead at Melbourne Park on Wednesday.
Defending champion Jannik Sinner dismissed eighth seed Alex de Minaur 6-3, 6-2, 6-1 to reach the Australian Open semi-finals and extend the country's decades-long wait for another homegrown singles winner at the Grand Slam on Wednesday.
It marks Osaka's first WTA 1000 semi-final since Miami in 2022, as the Japanese former world number one needed just over an hour to secure victory over the 10th seeded Svitolina.
In the evening session, men's third seed Alexander Zverev and women's fourth seed Jessica Pegula were forced off the court mid-match due to rain and the threat of lightning.
Anna Kalinskaya outclassed Britain's Emma Raducanu at the Washington Open on Saturday to advance to the final, where she will face Leylah Fernandez.
Iga Swiatek was the latest top player to suffer an upset loss in Montreal as the Wimbledon champion
Elena Rybakina powered into her first Cincinnati Open semi-final after stunning defending champion Aryna Sabalenka 6-1, 6-4 on Friday, while five-times Grand Slam champion Carlos Alcaraz recovered from a second-set blip to beat Andrey Rublev.
Carlos Alcaraz demolished Mattia Bellucci to banish memories of last year's shock early exit at the US Open on Wednesday.
American lucky loser Reilly Opelka put up an intense battle to stun top seed Daniil Medvedev 7-6(5), 7-6(5) and reach the semi-finals in Den Bosch on Friday.
The Americans found their rhythm to wrap up a final-day victory
IMAGES from Day 9 of the US Open, at the USTA Billie Jean King National Tennis Center, Flushing Meadows, New York.
IMAGES from Day 7 of the Wimbledon Championships, at the All England Lawn Tennis and Croquet Club, London, on Sunday.
Serbia's Novak Djokovic outclasses Russia's Andrey Rublev to set up a meeting with unseeded Tommy Paul in the semi-finals of the Australian Open on Wednesday.
Naomi Osaka felt the nerves but looked solid on her return to elite tennis after 15 months out as she got past Germany's Tamara Korpatsch 6-3 7-6(9) in the first round of the Brisbane International.
IMAGES from Day 10 of the US Open, at the USTA Billie Jean King National Tennis Center, Flushing Meadows, New York.
IMAGES from Day 5 of the US Open, at the USTA Billie Jean King National Tennis Center, Flushing Meadows, New York, on Friday.