The Supernatural star and his wife Genevieve Cortese, who married in 2010, welcomed their first child Thomas Colton in March.
Padalecki has now uploaded a picture of his son - wearing a patriotic babygrow - to his Twitter page in celebration of the Olympic Games.
"Thomas has some Olympic pride :)" he wrote. "GO USA!!!!"
Padalecki is currently filming the eighth season of Supernatural and recently dropped some hints about his character Sam's new romance in the upcoming episodes.
The series returns to The CW in the US on October 3. In the UK, season seven of Supernatural begins airing Wednesday, August 1 on Sky Living.
Watch celebrities discuss their favourite Olympic sports with Digital Spy below: