The winner of each event at this week’s championships effectively secures one of two Olympics places for each event, as long as the swimmer matches the qualification time.
Commonwealth champion James Wilby took silver behind Peaty but his time was 0.02secs outside the Olympic qualification time.
Elsewhere, Keanna MacInnes produced a shock in the 200m butterfly by pipping 2024 world champion Laura Stephens to secure her place.
She won the title in a Scottish record time of two minutes 7.24secs, but with Stephens also under the qualification time 0.13secs behind both are likely to compete in France.
Freya Colbert won the 200m freestyle but said she is unlikely to race the event in Paris because of a clash with the 400m individual medley – which she won at the World Championships earlier this year.
Colbert’s win secured her a place on the 4x200m relay team while Abbie Wood was also under the qualification time in second, meaning she is likely to race the event at the Olympics.
Kieran Bird swam a lifetime best to win the men’s 400m freestyle but his effort of 3:45.63 was an agonising 0.2secs outside the Olympic qualifying time.
The British championships are also fully integrated with the Para events, though Paralympic qualification takes a different format. Swimmers compete in mixed-classification races, then they are ranked in relation to their times to select a full squad.
In a competitive women’s 200m Para-freestyle race, five swimmers – Poppy Maskill, Olivia Newman-Baronius, Louise Fiddes, Jessica-Jane Applegate and Suzanna Hext – were all under the qualification time.
Maskill took the title to put herself in pole position for a place in Paris.
Elsewhere in the Para-swimming events, Sam Downie won the 400m freestyle title, Grace Harvey the 50m butterfly, Lyndon Longhorne the 150m individual medley and Harry Stewart the 100m breaststroke, although all four were outside the initial qualification time for the Paralympics.