Steinstad first represented Norway at the 2000 Summer Paralympics in Sydney, entering the long jump, 100 metre sprint and javelin throw events (F42). In the subsequent Paralympics after Sydney, Steinstad dropped the long jump and sprint events and focused on the javelin. He competed at both the 2004 Summer Paralympics in Athens and the 2008 Summer Paralympics in Beijing, finishing in the javelin sixth and tenth respectively. Paralympic success came in the 2012 Games in London, where he threw a distance of 48.90 to claim the bronze medal.