Flying back to Bangkok
The Chiang Mai–Bangkok route is one of Thailand's busiest domestic air corridors, with frequent flights throughout the day across multiple airlines, landing at either Suvarnabhumi or Don Mueang depending on the carrier — worth checking which one matches your onward plans, particularly if you have an international connection. The flight itself takes around 1 hour 15 minutes.
The overnight train south
The same sleeper service that runs up from Bangkok also runs the return leg, departing Chiang Mai in the evening and arriving into Bangkok's Krung Thep Aphiwat Central Terminal the next morning. It's a comfortable, scenic way to use an otherwise "dead" travel day productively, sleeping through most of the journey.
Overnight buses
VIP coaches run the return route overnight in a similar 9–11 hour window to the northbound journey, arriving into Bangkok's Mo Chit terminal. It remains the cheapest option, with the same trade-off of a longer, more tiring journey than flying.
Which to choose
If you have a flight out of Bangkok to catch, flying is the safest choice for predictability. If you've got a spare day and want to see the countryside one more time, the train is the better experience. See our Getting to Chiang Mai guide for the northbound comparison in more detail — the options and trade-offs are the same in both directions.