He won a Lindemann Trust Fellowship to do postdoctoral research at the University of California, Berkeley under Nobel Laureate Charles H. Townes, working on the Keck Aperture Masking Experiment.
Using the Keck Aperture Masking Experiment, Tuthill for the first time revealed pinwheel nebulae around Wolf–Rayet stars, formed by winds colliding with their binary companions.
The most spectacular of these have been conjectured as gamma-ray burst progenitors in the Milky Way: WR 104 and the only known Galactic Wolf-Rayet binary Apep.
Tuthill directed the Sydney University Stellar Interferometer (SUSI) at Narrabri, New South Wales from 2006 until its closure in 2017.
Tuthill is the director of the proposed TOLIMAN Space Telescope, funded by the Breakthrough Prize Foundation to search for planets around alpha Centauri AB by astrometry.