In his rookie season of 2002, Ó Sé impressed throughout the All-Ireland Senior Football Championship in a Kerry team under the management of his uncle Páidí.
Marc was given a torrid time as Kerry let what looked like a certain win with 25 mins to go slip and lost by a single point, 1-12 to 0-14.
[4] In 2005, Ó Sé continued to perform for Kerry who this time were narrowly defeated by Tyrone.
The team defeated Galway in the final of the National League again in a far less impressive game as the corresponding fixture 2 years earlier.
Kerry gained revenge against Cork in the Semi-Final before handing Mayo and even more severe beating than they had two years earlier.
The team advanced to the All-Ireland series, and reached the final, in which they beat Billy Morgan's Cork side 3-13 to 1-9.
Marc's performances were recognised as he won an All-Star and was named Texaco Footballer of the Year.
[7] In 2008, Ó Sé reached the National League and Munster finals with Kerry, but lost both.