He won the 2002 US Open boys' doubles title alongside compatriot Bas van der Valk where they defeated Brian Baker and Chris Guccione in straight sets 6–4, 6–4.

Koning made his ATP Tour debut at the 2002 Ordina Open where he was given a wild card entry into the doubles draw alongside Bas van der Valk.

[1] In June 2007, Koning made his ATP Tour singles debut when he prevailed through the qualifying rounds to reach the main draw of the 2007 Ordina Open played on grass courts in 's-Hertogenbosch.

[2] Koning has reached 7 career singles finals, posting a tally of 5 wins and 2 losses, all coming on the ITF Futures Tour.

Additionally, he has reached 19 career doubles finals with a record of 15 wins and 4 losses similarly all coming on the ITF Futures Tour.