In the UK, you can watch the first two seasons of "Smiling Friends" for free on Channel 4's streaming service, All 4, which hosts Adult Swim content. For Season 3, as of October 2025, it is available on HBO Max in the UK, following its October 5 premiere. You can stream the new season on HBO Max by subscribing, with plans starting at around £8-9 per month. Season 3 is expected to follow the same release pattern on Channel 4 as previous seasons, but currently the most reliable option is HBO Max for immediate access. You can also watch earlier seasons or episodes by buying them on platforms like Apple TV or Amazon Video. To summarize:

• Seasons 1 and 2: Available free on Channel 4 / All 4.
• Season 3: Available on HBO Max UK (subscription needed).
• Purchase options: Apple TV, Amazon Video for download.

Additionally, using a VPN to access Adult Swim's website can be an option, but the above are the official and straightforward legal options in the UK.