Underage

O'Connell's career with Kerry began in 1955 when he lined out in the Munster Minor Championship. Kerry lost the replayed Munster final to Tipperary.

Senior

He quickly joined the Kerry senior football team, making his debut in 1956 against Tipperary in the Munster Championship. He later lined out in the Munster final against Cork, but lost out in a replay. Two years later, in 1958, O'Connell won the first of eight Munster titles in-a-row; however, Kerry suffered a shock defeat by Derry in the All-Ireland semi-final. In 1959 O’Connell was captain when Kerry won the National Football League. He later guided his native-county to another Munster title; however, he had to retire injured in Kerry's All-Ireland victory over Galway.

Following a second National League victory in 1961 O'Connell captured his second All-Ireland medal in 1962 when Kerry defeated Roscommon in the final. A third National League victory quickly followed at the start of 1963. After two All-Ireland defeats by Galway in 1964 and 1965 Kerry surrendered their provincial crown to Cork in 1966 and 1967. O'Connell won a ninth Munster title in 1968; however, Kerry lost out to Down in the All-Ireland final. This defeat was followed by a great year of success in 1969 as O'Connell added a fourth National League medal to his collection before winning a tenth Munster title. He later won a third All-Ireland medal following a victory over Offaly.

In 1970 O'Connell entered the third decade of his inter-county football career, winning an eleventh Munster title in the process. A fourth All-Ireland medal quickly followed after a victory over Meath in the first 80-minute All-Ireland final. O'Connell claimed two more National league medals in 1971 and 1972, before winning his twelfth and final provincial medal in 1972. That year Offaly later defeated Kerry in O'Connell's last All-Ireland final appearance. In spite of this loss he was still presented with an All-Star award. O'Connell retired from inter-county football in 1973.