"Leo was paired with Rebecca Budig's Greenlee in 2000 and the two characters quickly became a soap super-couple," the network noted in a news release. "When Leo went over a waterfall years ago trying to save Greenlee, his body was never found, leaving daytime fans hopeful the character would someday return."
Duhamel, who is best known for his work in the "Transformers" film franchise, was nominated for four Daytime Emmy Awards during his time on "All My Children." He won an Emmy for Outstanding Supporting Actor in 2002 for his portrayal of Leo.
"Everyone at 'All My Children' is thrilled and excited to welcome Josh back to Pine Valley. The appearance of Leo is sure to be one of the highlights of the season," Julie Carruthers, executive producer of "All My Children," said in a statement.
The daytime drama began in 1970. ABC announced in April plans to cancel the show when this season wraps in September.