October 21, 2017
October 20, 2018
- Jace Norman as Henry Hart (Kid Danger)
- Cooper Barnes as Ray Manchester (Captain Man)
- Riele Downs as Charlotte Page
- Sean Ryan Fox as Jasper Dunlop
- Ella Anderson as Piper Hart
- Michael D. Cohen as Schwoz Schwartz
- Jeffrey Nicholas Brown as Jake Hart
- Kelly Sullivan as Kris Hart
- Matthew Zhang as Oliver Pook
- Joe Kaprielian as Sidney Birnbaum
- Winston Story as Trent Overunder
- Carrie Barrett as Mary Gaperman
- Tommy Walker as Drex
- Ben Giroux as The Toddler
- Mike Ostroski as Dr. Minyak
- Amber Bela Muse as Nurse Cohort
- Kevin Synoms as Bill Evil
- Matthew Patrick Davis as Kevin
- James Preston Rogers as Barge
Special Guest Cast
- 1. 10/21/17 - Sick & Wired (404)
- 2. 11/04/17 - Brawl in the Hall (405)
- 3. 11/11/17 - The Rock Box Dump (406)
- 4-6. 11/25/17 - Danger Games (401-403)
- 7. 01/15/18 - Toon in For Danger (411)
- 8. 02/10/18 - Meet Cute Crush (418)
- 9. 03/24/18 - Back to the Danger: Part 1 (407)
- 10. 03/31/18 - Back to the Danger: Part 2 (408)
- 11. 04/07/18 - Budget Cuts (410)
- 12. 04/14/18 - Diamonds Are For Heather (417)
- 13. 04/28/18 - Car Trek (412)
- 14. 05/05/18 - Toddler Invasion (416)
- 15. 05/12/18 - Captain Man-kini (420)
- 16. 05/19/18 - Saturday Night Lies (414)
- 17. 09/22/18 - Henry's Frittle Problem (415)
- 18. 09/29/18 - Spelling Bee Hard (419)
- 19. 10/06/18 - Up The Stairs! (422)
- 20. 10/08/18 - Danger Things (502)
- 21. 10/13/18 - Rubber Duck (409)
- 22. 10/20/18 - Flabber Gassed (501)
- Season 4 started production on April 3, 2017 and wrapped on December 15, 2017.
- Jace mentioned in an interview with Just Jared Jr that he wants to know a little bit more about Henry’s family.
- Henry Danger and Game Shakers had a crossover this season. 
- This crossover is the second crossover for both series and the second Dan Schneider universe crossover, after "iParty with Victorious".
- If you count "Game Shippers", this is the third Dan Schneider universe crossover, after "iParty with Victorious" and "Game Shippers".
- Jace Norman got a new hairstyle this season.
- When asked to describe this season in one word during an Instagram live stream, Riele said "awesome" and Sean said "cool".
- Starting from Toon in For Danger, Jasper has straight hair.
- The episode Toon in For Danger led into the animated show The Adventures of Kid Danger.
- Starting from Toon in For Danger, the show has new opening credits.
- Drex, Vice Mayor Willard, The Toddler, Frankini, and Goomer returned this season.
- This along with Game Shakers will be Dan's final live action series for Nickelodeon due to Nickelodeon not renewing his contract, plus some controversy with some behind the scenes drama.
- This is the last season where Schwoz is a recurring character. Starting in Season 5 he will be a main character.
- Episodes including Danger Things and Flabber Gassed were produced in Season 5, but moved to Season 4.
- This is the only season without an episode 1-Hour Event.