Kirjonen was born in 1993. Disabled since birth he has no function in both his legs. He took up athletics while still in secondary education. In 2011 he travelled to Dubai to compete in the World Junior Championships for Wheelchair Athletes. There he won both the men's shot put and javelin events.
In July 2012 he travelled to Staddskanaal to represent Finland in the IPC Athletics European Championships. There he collected the bronze medal in the men's F55/56 javelin throw. He followed this by being selected to represent Finland at the 2012 Summer Paralympics in London, again in both his favoured throwing events. In the shot put, a joint F55/56 event, his best throw in the first round of 11.89m only gave him enough points to finish 11th, denying him the chance to progress to the final round. In the javelin Kirjonen threw 26.36 in his first throw, but fouled his remaining two attempts leaving him outside the top eight after the first round.
The following year he was back on the podium when he competed in the 2013 IPC Athletics World Championships in Lyon. He competed in a joint F55/56 shot put finishing third to take the bronze medal.