The official of the Ghanaian lower tier side claims the striker has penned a deal that is set to keep him at Stade Louis II until 2023 following a successful medical.
The 18-year-old was earlier linked to Portuguese side FC Porto.
“Ayiah has signed a five-year contract with AS Monaco after passing his medical," Amoah said in Ghana on Thursday.
“We [Charity Stars] believe the club is the best destination for him to continue his development.
"We’ve seen what the club has done with unearthing big players like Kylian Mbappe and believe moving to France with Monaco will help him.”
Ayiah first made headlines last year when he netted four times to finish second top scorer at the Africa Under-17 Cup of Nations.
Captain of the Black Starlets, the attacker perpetuated his good form at the World Cup in India five months later, scoring three times to help the two-time champions make the quarter-finals.
His exploits earned him a nomination for the Youth Player of the Year gong at the 2017 Caf Awards.
He is a current member of Ghana's under-20 side.