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The 22-year-old heptathlete from Liverpool set a national indoor record with her third jump to win the event.
Johnson-Thompson broke the British high jump record last week with 1.97m and also set a hurdles personal best.
"I jumped a PB and ran a PB in the hurdles last week, so I knew I was in all right shape," she told BBC Sport.
Johnson-Thompson missed last summer's Commonwealth Games and European Championships with a foot injury.
She now heads to next month's European Indoor Championships in Prague, where she will compete in the pentathlon.
"I'm happy with it but I'm like 'right, let's move on from this,'" she added. "I'm just so happy to be in good shape, competing and healthy and happy. I'm not going to take it for granted any more."
Olympic champion Greg Rutherford set four indoor personal bests on his way to winning the men's long jump with a 2015 world leading 8.17m, one centimetre short of the national record.
The 28-year-old looks likely to stick with his plan of skipping Prague to focus on winning a first world outdoor title later in the year.
"I don't know now," he said. "It's a possibility but it's a slim one. I think probably not still. I never planned to do it and never set it as a target.
"We've done one jump session and one run-up session in the build-up to this and the rest has been weight sessions, so we'll see.
"If it was any other year then I'd consider it, but I'm so determined to win the World Championships this year and I do believe I can do that."
World number one Jenny Meadows won the 800m in a time of two minutes 01.25 seconds, while Nigel Levine won the 400m in 46.43secs ahead of compatriot Jarryd Dunn.
The 60m was won by 38-year-old Kim Collins of Saint Kitts and Nevis in 6.50 seconds ahead of Britain's Chijindu Ujah (6.55).
Katarina Johnson-Thompson set a second British record within a week as she won the long jump with a leap of 6.93m at the Birmingham Indoor Grand Prix.