Brett received a PhD in 1995 from UNSW and has held Postdoctoral positions at Stanford (NASA Fellow) and Humboldt University Berlin (Alexander von Humboldt Fellow). His first postdoctoral research program, with Professors Don Lowe and David Relman was the first investigation of microbial life associated with stromatolites using modern molecular biological and phylogenetic techniques . Since 1998 he has been a Fellow of the Australian Research Council at UNSW. He is considered to be one of the world's leaders in the genetics of toxic cyanobacteria (blue-green algae). The results of his basic research and his other work on the evolution of cyanobacteria has revolutionised an entire field of environmental science. He is also engaged in “molecular bioprospecting”, which has led him to study the secondary metabolism of microorganisms from unique environments, such as Antarctica and the hypersaline coasts of Shark Bay in Western Australia. He has been awarded the Australian Academy of Science Fenner Medal in 2004 and the Eureka Prize for Scientific Research in 2001 and 2005.