King was ruled out after he sustained a side strain during West Indies' defeat to England in their Super 8 opener earlier in the week. The right-handed opener was helped of the field after he seemed to have injured himself when batting on 23 off 12 balls.
Cricket West Indies had waited for the results from the MRI scan and upon receiving the report, confirmed that King would take no part in the tournament with Mayers, who was part of the reserves, being approved as his replacement.
"The Event Technical Committee of the ICC Men's T20 World Cup 2024 has approved left-handed batter Kyle Mayers as a replacement for Brandon King in the West Indies squad.
The replacement of a player requires the approval of the Event Technical Committee before the player can be officially added to the squad," ICC said in a statement.
Now, the left-handed opener will come in as a replacement player for the co-hosts for the rest of the tournament.
He is expected to join the squad on Saturday (June 22).
During the game against England on Wednesday, King was flying high in the powerplay. He raced 23 in just 12 deliveries and started to lay the foundation for a 200-plus total for the West Indies.
He smoked the ball out of the stadium with a 101-metre six off Reece Topley, resulting in a replacement ball. But he got injured in the 13th delivery of his knock. He charged down the pitch to hit Sam Curran through the cover region.
King went one more step before collapsing and being forced to quit injured after receiving care from a West Indies medical staff.
King did not field in England's run chase of 181, with Shimron Hetmyer filling in as a substitute fielder, and CWI released a statement to confirm he suffered a side strain.
King getting ruled out of the tournament has put a big dent in West Indies' chances of lifting the coveted title. He has been the leading run-scorer for the Caribbean side in T20Is since the beginning of 2023. King has racked up 651 runs in 23 innings, which includes four fifties.
His replacement, Mayers, has enjoyed a decent run in 2024.
The left-handed opener has featured in 11 T20I games this year and amassed 367 runs at an impressive strike rate of 155.50.
In King's absence, Shai Hope played in the Super 8 match against USA as Mayers will only link up with the squad in time for West Indies' final Super 8 clash against South Africa on Sunday (June 23).