He was a pioneer of the theory of cosmic inflation, for which he received the 2014 Kavli Prize in Astrophysics together with Alan Guth and Andrei Linde.

In 1973, building on Zeldovich's prior research, he showed that, according to the uncertainty principle, rotating black holes must emit particles.

[13] He would later conjecture that all black holes (not just rotating ones) emit energetic particles, a theoretical effect known today as Hawking radiation.

[17][19] Around the same period, Alan Guth independently proposed a theory of exponential expansion, which he termed 'inflation', to tackle the horizon, flatness and magnetic monopole problems with the Big Bang.

[22] Viatcheslav Mukhanov and Gennady Chibisov proposed that these quantum fluctuations eventually resulted in the largest structures in the universe.

[27] He and Mukhanov were joint recipients of the 2009 Tomalla Prize for their contributions to cosmological inflation, with Starobinsky specifically recognised for his calculations of the gravitational radiation emitted during the inflationary epoch of the universe.

[2][29] Starobinsky and Mukhanov were also co-recipients of the Amaldi Medal from the Italian Society for General Relativity and Gravitation in 2012 and the Gruber Prize in Cosmology in 2013.

[30][31] Together with Alan Guth of MIT and Andrei Linde of Stanford University, Starobinsky was awarded the 2014 Kavli Prize in Astrophysics by the Norwegian Academy of Science and Letters for his pioneering contributions to the theory of cosmic inflation.

[32] In 2019, he was a co-recipient of the Dirac Medal of the International Centre for Theoretical Physics together with Mukhanov and Rashid Sunyaev for his work on the cosmic microwave background.