Kearney and Summers-Newton's efforts brought Britain level with Paralympic heavyweights China in the overall medals table on six golds.
Kearney, 27, who was born with cerebral palsy, defended her title in the 100m freestyle S5, less than 24 hours after also winning the 200m freestyle.
"To retain my title feels incredible," she said. "It was such a late night and early start and not long to rest in between.
"It was really hard for all of us who swam last night to keep the energy up," she added.
Summers-Newton, who was born with achondroplasia; a condition that affects how bones develop, also held on to her title from the Tokyo Paralympics three years ago but in the women's 200m individual medley SM6.
"I was really nervous, it's something that's come from Tokyo," she told reporters.
"There's a lot of pressure being Paralympic champion," the qualified primary teacher added.
In other events in the La Defense Arena pool, Hong Yang added a third swimming medal for China as he won the 200m individual medley SM6.
Israel's world record Ami Omer Dadoan followed up his Paralympic record time in the heats of the 100m freestyle S4 with gold in the final.
The highlights later on include Belarussian Ihar Boki, forced to compete as a neutral Paralympic athlete because of his country's role in Russia's invasion of Ukraine, eyeing an 18th gold medal as he swims in the 100m backstroke S13 final.
