The 29-year-old was denied a chance to fight for a bronze medal after he lost to South Korean Jun Ho-Cho and Georgian Lasha Shavdatuashvili, eventually finishing seventh at the ExCeL.
Norlfolk-based Oates, making his Olympic debut, was delighted with the reaction of the crowd, but was left frustrated by losing in a sudden death scenario.
“It was disappointing for me,” said Oates, who defeated Australian Ivo Dos Santos in his first bout and then Tsagaanbaatar Khashbaatar of Mongolia.
“I think I may have fought the best I’d ever fought – I think the Mongolian fighter I faced in the second round has been the most consistent and best fighter in my weight category over the last few years.
“He’s been world champion, won world bronze and been at the top of the rankings so it was a really good win to get past him. In the fight I went for a big score, it was make or break and I got caught.
“The atmosphere has been phenomenal and I really hope it spurs on the rest of the guys and girls to take a medal.
“With that behind them we have great fights and as you’ve seen today upsets are there for the taking.”
The crowd at the ExCeL were hoping for Team GB’s first judo gold medal ever but defeat to Shavdatuashvili ended those hopes.
More disappointment was to come when he returned to action in the repechage to face South Korea’s Jun-Ho Cho, meaning that Oates left his debut Games without a medal.