Armstrong led the team that won a competition to design the new east London festival venue, which was created on a former derelict dock. She is also the creative director of the Shangri-La area at Glastonbury Festival.
Difficulties have arisen over capacity at London Pleasure Gardens since the site opened in June. Bloc Weekend festival was shut down by police on its first night after serious overcrowding and the capacity for Last Mile Festival and the Africa Stage at BT River of Music were both reduced.
In a blog post yesterday, Armstrong wrote of the Pleasure Gardens: "I don't feel now like its [sic] following the vision that we set out to do... Hopefully the road will swing toward it again at some point."
In a statement, Armstrong said: "It is with the deepest of regrets that I announce my resignation from London’s Pleasure Gardens. I am enormously proud of the huge transformation that my team and I have achieved so far.
"In only three months, we remediated what was for decades a blighted, inaccessible and formerly contaminated site. We've built the foundations of the Pleasure Gardens vision - a unique public leisure and cultural space in London.
She added: "We have seen but the first inkling of what LPG can be and I do hope its artistic and cultural potential is supported moving into 2013 and beyond. The cultural and regenerative work we have done is certainly the most extraordinary test case."
London Pleasure Gardens did not respond to Event's request to comment this morning.
Armstrong will now work on transforming the O2 arena for Radiohead and redesigning the Shangri La area of Glastonbury for 2013.
What does the future hold for London Pleasure Gardens? Comment below and let us know.
For more in-depth and print-only features, showcases and interviews with world-leading brands, don't miss the next issue of Event magazine by subscribing here.