[5] O'Shea made his first appearance for the Kerry senior team on 6 August 1950 in a challenge game against Wexford to mark the official opening of Con Keating Park in Cahirciveen.
After the final trial and team selection he was listed as an official substitute with a strong possibility of coming on during the game.
However, O'Shea had played illegally for club side Mitchelstown on the day of the drawn game and had to withdraw from the panel.
[citation needed] On 9 March 1952, O'Shea made his competitive debut for the Kerry senior team in a 1–09 to 1–07 defeat of Mayo in the National Football League.
[7] O'Shea retained his place on the Kerry panel in 1954, however, he found it difficult to break back into the starting fifteen.
On 25 July 1954, he won a second Munster Championship medal after being introduced as a substitute for John Cronin in a 4–09 to 2–03 defeat of Cork in the final.
By this stage he had reestablished himself on the starting fifteen as left corner-back and was selected in that position for the All-Ireland final against Dublin on 25 September 1955.
[citation needed] O'Shea won his sole National Football League on 10 May 1959 after a 2–08 to 1–08 defeat of Derry in the final.
[citation needed] On 24 July 1960, O'Shea won a sixth Munster Championship medal when Kerry defeated Waterford by 3–15 to 0–08 in the final.