The 18-year-old joins the English rugby union club after making five appearances for the Sharks' Under-19 team in their opening five matches this season.
"I am very grateful to the Sharks for the opportunities they have given me, but the chance to join London Irish was too good to deny," said Palframan.
London Irish's director of rugby Brian Smith hailed Palframan as "an outstanding prospect".
"He is a very physical player and exceptionally good with ball in hand," he said.
"He will work with Glenn Delaney to enhance his all-round game and continue his progression.
"We believe we have real gem on our hands."
Palframan is 6"1' tall and weighs 118kg.