The French designer created the furniture to bring colour and fun to the central London street, while also being a practical addition as the pedestrianised street previously had no public seating.
"I wanted to not only bring some colour to the street but to do something more interactive, more sculptural," Walala told Dezeen.
"I wanted Walala Lounge to be surprising and out there but also comfortable and home-like. And now that the benches are in place, it seems crazy that they weren't there all along."
Built as part of this year's London Design Festival for developer Grosvenor, but set to say in place for a year, the installation consists of 10 sculptural benches and a series of cube-shaped planters.
Each of the pieces, which were designed with Walala's creative producer Julia Jomaa, has been designed as a family of furniture that will bring joy to visitors to the street.
"Cities can be so grey, it can feel really oppressive sometimes. I want to change how it feels to live in a big city, to inject some colour and light into people's days," said Walala.
"It means so much to me when I can make people smile. That's how I feel I can have the most impact on the world. To take what I care about and share it with others."
Constructed from brushed steel and MDF, each of the benches has a geometric form made from a combination of cuboids, cylinders and arches. Although they each have a unique shape, the benches are united by Walala's signature colours and graphics.
"They are all brought together by my use of colour and texture, but also how they sit sculpturally together and with the architecture that surrounds them. They're all in conversation," said Walala.
"It's so difficult to decide [which is my favourite]! I was giving a tour of the benches recently, and I kept saying different benches were my favourite," she continued.
"But one that really stands out for me is the blue zigzagged one, about halfway down the street. When it is photographed it almost looks like it has been drawn into the photograph. I like that interplay between 2D and 3D."
Walala created the colours and patterns through a process of experimentation, until she found combinations that worked for the street-wide installation.
"I work very intuitively through any project. From early collaging and notebooks, to playing with materials and objects in space," she explained.
"Even though something might make sense on an architectural drawing or a computer render, it has to feel right in reality. There are practical challenges too, which I love responding to. A certain architectural detail, or like with South Molton, the sense of space along the street."
Walala established her east London studio in 2009. At previous editions of London Design Festival she has created an inflatable castle and a multicoloured pedestrian crossing in south London. She has also created much large installations, including a 40-metre-high mural in New York.
She believes that when colour and fun are added to cities it can make a big difference to people's experiences.
"The smaller details are always so important. Small changes can build up to something much bigger, but also just a slight tweak can be surprising and therefore very powerful," said Walala.
"It all leads somewhere. But also why do we have to stop at small changes? I want artists and designers to be involved in the city in much bigger ways."
Photography is by Charles Emerson.