In 2017, Barish was awarded the Nobel Prize in Physics along with Rainer Weiss and Kip Thorne "for decisive contributions to the LIGO detector and the observation of gravitational waves".

[15] Among others, these experiments were the first to observe a current that was weak and neutral, a linchpin of the electroweak unification theories of Salam, Glashow, and Weinberg.

In the early 1990s, he spearheaded GEM (Gammas, Electrons, Muons), an experiment that would have run at the Superconducting Super Collider which was approved after the former project L* led by Samuel Ting (and Barish as chairman of collaboration board) was rejected by SSC director Roy Schwitters.

He led the effort through the approval of funding by the NSF National Science Board in 1994, the construction and commissioning of the LIGO interferometers in Livingston, LA and Hanford, WA in 1997.

He has chaired the Commission of Particles and Fields and the U.S. Liaison committee to the International Union of Pure and Applied Physics (IUPAP).

[24] The ILC is the highest priority future project for particle physics worldwide, as it promises to complement the Large Hadron Collider at CERN in exploring the TeV energy scale.

This ambitious effort is being uniquely coordinated worldwide, representing a major step in international collaborations going from conception to design to implementation for large scale projects in physics.

"[31] Barish was a recipient of the 2017 Giuseppe and Vanna Cocconi Prize[32] of the European Physical Society for his "pioneering and leading role in the LIGO observatory that led to the direct detection of gravitational waves, opening a new window to the Universe."

Barish was a recipient of the 2017 Princess of Asturias Award for his work on gravitational waves (jointly with Kip Thorne and Rainer Weiss).

[35] In 2017, he won the Nobel Prize in Physics (jointly with Rainer Weiss and Kip Thorne) "for decisive contributions to the LIGO detector and the observation of gravitational waves".

[38] In 2023, he was awarded the inaugural the Copernicus Prize, bestowed by the government of Poland on "those who made exceptional contributions to the development of world science.

His leadership of the Laser Interferometer Gravitational-Wave Observatory led to the first detection of gravitational waves from merging black holes, confirming a key part of Einstein's Theory of Relativity.