[9] He studied English and Economics at Stanford University, before receiving an MFA in fiction from the Michener Center for Writers.

In addition to his writing, he has worked as an editor in San Francisco, a consultant on economic and urban planning in New York City, and a researcher in Bangalore.

Mahajan's first novel, Family Planning, was described by the San Francisco Chronicle as "Brave, breakneck, and amusing"';[10] in The Seattle Times as "Pleasurably crazed";[11] and in the Washington Post as "Genuinely funny" and "Profound".

"[14] Family Planning was published by the Harper Perennial imprint of HarperCollins, and released in the US in 2008 and the UK in 2009, with translations forthcoming in India, Germany, Italy, Spain, France, Brazil, and Korea.

[17] The judges of the National Book Award for Fiction described the novel as an "epic tableau drawn by the instruments of empathy, an illuminating human expedition from India to America and back, a story that burns straight through you—incandescent, absorbing, engrossing—a novel of hope and despair, love and rage, today and tomorrow.