Rachel Brooks works with illusory and atmospheric space, creating heavy edged, uneven forms which appear to slide off her canvases. Her compositions are achieved by varying the intensity and concentration of paint, fading each plane out to a flat, dry edge. Working on canvas or paper, Brooks combines the use of a palette knife with fingers swirling repeatedly into the paint. The scale of each gesture is varied; small concentrated motions suggest an illusory space while larger sweeping marks work to lighten and flatten the space. The works can be read from several vantage points: what is a large block of colour from a distance becomes a subtly variegated, meditative pattern on closer inspection. More recently, Brooks has begun to work upon acetate and other transparent surfaces. Her Perspex and oil Dragonfly Wing series is an extension of this practice.

Brooks' work is held in numerous private collections throughout New Zealand including those of The Arts House Trust and the Waikato Institute of Technology.