Having won the T44/46/47 200m on Monday, Arnott added the 100m T43-47 gold to his collection, clocking 11.45 seconds.
Japan’s Jajimu Ashida was second in 11.64 seconds, with Bahrain’s Elyas Alyasi third in 11.81.
Arnott is one of three City of Plymouth AC athletes on Great Britain duty this week.
Veteran Simon Anderson is in Korea competing at the World Masters’ Championships. He finished fourth in the cross country event on Monday will compete in the indoor 3,000m on Thursday and the 1,500m on Saturday
Meanwhile on Sunday, Victoria Weir will run for GB in the junior women’s race at the IAAF World Cross Country Championships in Uganda.
Elsewhere, another Great Britain junior international, Erme Valley’s Will Battershill, opened his outdoor season by winning the 2,000m steeplechase at the Cougar Spring Beck International in Houston, Texas.
Running for Harvard University, Battershill eased to victory in a time of 6:03.72