The 23-year-old defender joined the Eagles in the summer of 2022 from Northern Ireland Football League Premiership side Larne FC.
He was a prominent figure for Palace Under-21s in 2022/23, making 33 appearances in all competitions. Balmer also featured for the first-team in their mid-season friendlies against Real Valladolid and Botafogo, while also earning his first senior call-up to the Northern Ireland national team.
The centre-back then moved to Port Vale on a half-season loan at the start of 2023/24, helping them to an EFL Cup quarter-final, before moving to AFC Wimbledon for the remainder of the campaign in January.
He will now make the switch north of the border to Motherwell on Monday, 1st July, as they prepare for their fortieth season in the Scottish top flight.
Everyone at Crystal Palace wishes Kofi the very best for the rest of his career.