Does anyone know how to go from Chiang Mai to Chaiyaphum by bus? Any information is greatly appreciated!

You might ask at the bus station if a bus to Khon Kaen stops at Chum Phae, and also ask how to get from Chum Phae down to Chaiyaphum city, if that's your destination. Believe there are local buses from Chum Phae heading south.

Mac

The best way for us was to take the overnight bus from Chiang Mai to Korat on Nakhorn Chai Tour then we took a bus from Korat to Chaiyaphum, which was about 2 hours.

Nakonchai air does go through Chaiyaphum but we would of arrived there around 2-3 AM.

zeekgarcia has it, nr 1 is not really needed.

NKAir also has DAYtime buses ChMai-Khorat, several, a few of them also with stop in CP-I guess the best way. or if a midofnight arr does not suit you-go onward to Khorat and turn back after breakfast.

In general these Qs are COMPLETELY superfluous to worry about-simply go to busstation, go to info or look lost and someone will point you to right counter. If change is needed, they will tell you-and instruct busstaff to watch about you.

Also: do not worry about booking and all that. NKCair has a website, but its only in Thai, it allows bookings, but only with a Thai bank, on normal days there is always space at last minute. TV-dedicated users only want the super prestigious superdeluxebus-but that wont do the intermediate stops.

In my experience Nakhonchai Air rarely still have seats available on the day of departure, although admittedly that's for the CM - BKK route which is obviously very popular.

FYI their "First Class" buses are actually the nicer than the "VIP" but for CM - Korat you may have no choice anyway.

Not sure they'll speak English but you can call them to book then pay at 7/11 using a code - very convenient. 02 9363000.

Good luck.

..... And I've just realised your original post is from June. Oh well, maybe someone else can benefit from the info given.