It is Källberg's second straight 3-0 victory at the WTT Champions in Macao, the tournament that includes only 32 players.
Now the Swede, ranked 16th in the world, remains among the last eight.
Coton, ranked 21st in the world, knocked out fourth-seeded Lin Yun-Ju of Taiwan in the first round. He had nothing to gain against Källberg - the match was over in 20 minutes.
I'm happy with a lot of things, I served well and didn't let him attack like he wanted. I'm super happy about a lot, says Källberg.
The quarterfinals will feature the winner between Benedikt Duda of Germany and Alexis Lebrun of France.
Truls Möregårdh plays his round of 16 on Friday against Japanese Shunsuke Togami.
