- Lizzy Greene as Dawn Harper
- Casey Simpson as Ricky Harper
- Mace Coronel as Dicky Harper
- Aidan Gallagher as Nicky Harper
- Allison Munn as Anne Harper
- Brian Stepanek as Tom Harper
- Kyla Drew Simmons as Mae Valentine
- Main article: Episode Guide
These are episodes that have confirmed titles and dates.
These are episode titles that have been confirmed, but the airdate is unknown.
- Dude, Where's My School? (401)
- 402 (402)
- It's a Hard Knocks Life (403)
- Sympathy for the Squishy (404)
- Leader of the Stack (405)
- The Harper Quad-Jobbers (406)
- 407 (407)
- Quadentity Crisis (408)
- Quadbusters (409)
- We'll Always Have Parasites (410)
- Quadcodile Dundee - (411)
- House Crushing for Dummies (412)
- Quadspiracy Theory (413)
- Lasties with Firsties (414)
- Season 4 was confirmed on March 20, 2017.
- Season 4 is a short-length season with only fourteen episodes.
- Lizzy Greene confirmed they had started filming Season 4 on May 9, 2017 and Aidan Gallagher confirmed they had finished filming on September 20, 2017.
- Mace Coronel mutually parted ways with Nickelodeon and left the show in August 2017. He will not appear in the last five episodes.
- On Instagram, Kyla Drew Simmons, Allison Munn and Aidan Gallagher made it seem like this was the last season as Nickelodeon does normally end a show at four seasons.
- Following Mace's exit from the series, many of the cast members including Lizzy and Aidan have already posted on social media that they're saying goodbye to their characters, implying that this is the final season.
- The season premiere will be Dude, Where's My School?.
- The season finale will be Lasties with Firsties.
- Miles might turn into a main character in this season.
- Aidan Gallagher's voice got deeper this season due to puberty.