The fourth season of The Backyardigans aired from October 1, 2009 to May 3, 2010. It contains twenty episodes.
- This is the second and final season in 16:9 widescreen and with a picture format of HDTV/1080i.
- Nickelodeon did not normally air episodes from this season in widescreen format until July 2013.
- This season is available on Nickelodeon's video-on-demand service.
- This season has been released to the Canadian iTunes store.
- Chris Grant Jr., becomes the new voice for Tyrone in this season
- Uniqua, and Austin, get new singing voices in this season. Avion Baker, and Nicholas Barasch respectively.