Police said Brian Andrew Burggraf, 27, was arrested at 1am while walking on a road in Tambon Jed Yod.
Police say they found a 15-centimetre-long knife in his trouser pocket along with a packet of hashish marijuana.
Police claim Burggraf confessed to attacking the Dutch father and son, identified as Erik Jan, 52, and Colin Mike, 20.
The victims were among a group of eight Dutch tourists walking along the ancient Chiang Mai moat when they were stabbed at 9pm.
