After a period of post-doctoral research with George Sheldrick at the University of Göttingen, Brooker returned to New Zealand to take up a lectureship in chemistry at the University of Otago in 1991. She rose to become a full professor in 2006.
Brooker's research is in the fields of transition-metal and macrocyclic chemistry. Her work has included the development of molecular switches and molecular magnets, with potential application in nanodevices.