Van den Nieuwelaar was born in Tilburg in 1944. He studied at the Academy of Art and Design in Breda. Before founding his own studio in 1969, he worked for several architectural firms. As a designer and architect, he came up with lamps, furniture, cabinets and rugs. In 1968, a year before he established himself as an independent designer, Van den Nieuwelaar drew an innovative series of fluorescent lamps in which the light source was the starting point. The shape of the light source determined the design for the various luminaires of the TC Series (Tubular Construction), with the TC-6 Circular Lamp being the best-known icon.
Van den Nieuwelaar's designs can be recognised by their geometric shapes. He liked to work with a minimum of materials. Typical Van den Nieuwelaar furniture is characterised by simplicity and clarity in form and material. He drew inspiration from Rietveld and De Stijl, the Bauhaus of the 1920s. His now-famous designs were featured in exhibitions at Museum Boijmans van Beuningen in Rotterdam, the Stedelijk Museum in Amsterdam and the Museum of Modern Art in New York. For Pastoe, Van den Nieuwelaar designed the iconic Amsterdammer cabinet, known for its roller shutter as a cabinet door. Aldo van den Nieuwelaar's work is included in various museum collections including those of the Stedelijk Museum Amsterdam, Boijmans van Beuningen and the Museum of Modern Art in New York.
Van den Nieuwelaar also achieved fame as an architect. For instance, he was responsible for the design of the Waterlooplein underground station in Amsterdam. Light was a theme frequently seen in his oeuvre. Van den Nieuwelaar was asked to design the lighting in several public spaces. In 1980, he was awarded the American Society of Interior Designers (ASID Award) and in 1986 he received the Kho Liang le Prize, a Dutch industrial design prize, awarded annually from 1979 to 2002 to a designer based in the Netherlands.