The 37-year-old from Farnham, whose family hail from Pembrokeshire,finished ahead of China's Lili Wang.
Brecon's Robert Davies is guaranteed at least silver after reaching Tuesday's men's class one table tennis final.
In the men's F41 javelin, Kyron Duke was less than two metres away from earning a podium spot.
"It feels a bit unreal because I had such an appalling start," said Morris after her win.
"It shows that if you have stuff drilled into you day in, day out with coaches telling you what to do, that plan works."
Davies secured a 3-1 win over Hungary's Endre Major and goes into the final hoping to underline his billing as the world number one in his category.
Duke was realistic, and is already looking forward: "I can't ask for anything better, it is not a medal but it is as good as. I have done my best and come out at the top of my game," he said.
"I'm really looking forward to the World Championships back at home next year and then I've got my eyes set on Tokyo 2020.
"I'm hungry for it - I'm getting closer and closer. I threw a PB today so it is going to come. Not everyone gets what they want straight away, things take time. But I have the determination and will put in the hard work to get there."
Sprinter Rhys Jones, a bronze medallist at the 2014 Commonwealth Games, finished sixth in the final of the T37 100m.
T38 long jumper Olivia Breen finished 12th in the final, with a best effort of 3.99m.
Jordan Howe has qualified for Monday's T37 200m final after he finished third in his heat in a season's best time.
Sara Head's hopes of an individual medal in the women's singles class three table tennis came to an end at the quarter-final stage.
Head lost 3-0 to Chinese world champion Li Qian and she will now turn her attention to the women's team event.
Archer Dave Phillips helped GB reach the mixed team recurve quarter-finals, where they lost to Iran.
James Ball and pilot Craig Maclean set the pace in the men's tandem B 1000m time trial final, but eventually finished fifth as Great Britain team-mates Neil Fachie and Pete Mitchell won silver.