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.
Police say the suspect gave no reason for perpetrating the attack.
Eyewitnesses told police that Burggraf walked up behind the group of Dutch tourists before launching the frenzied attack.
Jan suffered a 10-centimetre-long cut to his throat and two stab wounds in his back while his son was left with a long, deep gash on his arm.
The two were rushed to the Chiang Mai Hospital after police were alerted of the attack.
Local residents told police that Burggraf may have attacked another foreign tourist with a knife in the same area. The unidentified tourist was also stabbed in the back. Locals said the clothes Burggraf was wearing matched the description of the perpetrator in the earlier attack.