Between 1956 and 1964, he won a total of 13 medals (seven gold, four silver, two bronze) with his strongest individual event being the pommel horse in which he won gold in 1960 and 1964. His 13 Olympic medals was a record for men until it was bettered by fellow Soviet gymnast Nikolay Andrianov.
He also won a total of 14 medals at the World Championships. Shakhlin won four individual titles at the 1958 World Championships: all-around, horizontal bar, parallel bars, and pommel horse. Unusually tall for a gymnast, his height and reach were a distinct advantage on the horizontal bar but caused him difficulty on the floor exercise.