Rebecca Adlington secured her spot in the British Olympic team with a commanding performance in the 400m freestyle at the national trials.
She was one of six swimmers to book places for London 2012 at the British Swimming Championships on Sunday.
Jo Jackson (400m free), Ellen Gandy and Fran Halsall (100m fly), and Daniel Sliwinski and Craig Benson (100m breast) also secured their spots.
World 50m backstroke champion Liam Tancock reached the final of his event.
An emotional Adlington told 5 live sports extra she was nervous before the race, describing the trial as the biggest of her career.
"I wasn't even bothered about the time, I just wanted to get in," said Adlington, who became a household name after winning gold in the 400m and 800m freestyle in Beijing in 2008.
"Four years it has taken to get to this point and you can't imagine how good it feels to get here."
The 23-year-old from Mansfield led from start to finish and seemed on course for a British record before easing to victory in 4:02.35, ahead of Jackson.
Adlington's time was faster than the times she recorded to win the Olympic title and the silver medal at last year's World Championships.
"I'm so relieved," said Olympic bronze medallist Jackson, who has suffered with illness since the autumn of 2009.
"I've had my struggles the past few years but for me it's a massive positive. I've made the Olympics. It's going to be my third Olympics and I'm so excited."
It was an evening of high-quality competition at the Aquatics Centre, which is hosting its first competitive swimming meeting.
To qualify for the Games, swimmers need to finish in the top two of their event and also make the 'A' standard time and it was a requirement that posed little difficulty for Gandy.
She pipped Halsall in the final lengths of the 100m butterfly to touch in 57.25, chopping 0.15 secs off the British record set by Halsall in 2010.
"It's the greatest feeling ever," said the Melbourne-based Gandy, who won silver in the 200m butterfly at the World Championships.
"All I've wanted to do for the last four years is to be able to say 'I'm going to the London Olympic Games' and now I can say it. I am just over the moon.
"The time was a bit irrelevant to me because I just wanted to make the team. I'm thrilled I got the British record. I think Fran was beating me most of the way but I think my 200m training helped me down the last 25 metres."
Halsall said she would go back to analyse her performance after being disappointed with second.
"Everything I've done in training has been going so well and it indicated I'd swim a lot faster than I did," she said. "But I'm on the team now and that is all that matters. It's faster than I've ever done at this time of year before."
Such was the quality of the race, Jemma Lowe - finalist in Shanghai in both butterfly categories - missed out on an Olympic place, although she still has a chance of making the team in the 200m butterfly.
"Obviously I am really disappointed," said Lowe. "One of us had to come third and it was me."
British record holder Sliwinski won the 100m breastroke and will be joined on the team by 17-year-old world junior champion Benson, who finished second from lane six to take the total of qualifiers for London 2012 to 11.
"I went in thinking I could do it but to actually do it is amazing," said Benson. "I am totally in shock."
The GB Paralympic trials are also taking place at the Aquatics Centre and Nyree Kindred produced an astonishing performance to make the team in the 100m backstroke, eight months after giving birth.