Merrick, who had the old Railway Stand at St Andrews named after himself at the beginning of this season, died peacefully on Wednesday afternoon.
Joining Blues in 1939, he made a total of 551 appearances for the club over two decades including one FA Cup Final appearance in 1956.
He was regarded as one of the best goalkeepers in the country in the 1950's and between 1951 and 1954 he won 23 caps for England.
After retiring at the end of the 1959-60 season he was named manager of the club and led Blues to victory against arch rivals Aston Villa in the League Cup Final in 1963.
He resigned from the managers position in 1964 and later took up a similar role at Bromsgrove Rovers and Atherstone Town.
A true Blues legend - may he rest in peace.