His research included data privacy, web search, robotics, and computational drug design.

Motwani was one of the co-authors (with Larry Page and Sergey Brin, and Terry Winograd) of an influential early paper on the PageRank algorithm.

[10] He was an avid angel investor and helped fund a number of startups to emerge from Stanford.

He sat on boards including Google, Kaboodle, Mimosa Systems (acquired by Iron Mountain Incorporated), Adchemy, Baynote, Vuclip, NeoPath Networks (acquired by Cisco Systems in 2007), Tapulous and Stanford Student Enterprises.

[14][15] Motwani was found dead in his pool in the backyard of his Atherton, San Mateo County, California home on 5 June 2009.

The San Mateo County coroner, Robert Foucrault, ruled the death an accidental drowning.