Indian-American Shalabh Kumar, founder and president of the Republican Hindu Coalition (RHC), met with Donald Trump in July at the residence of Mr Mnuchin in Southampton, New York where he discussed his vision for the campaign.
"Trump agreed to participate," RHC said in a statement. Mr Kumar, who played a leading role in mobilising Indians for Donald Trump has been appointed to the Transition Finance and Inauguration teams, the media release said.
"I am honoured to accept these positions with the transition team and the inauguration committee," Mr Kumar said in a statement in which he congratulated Mr Mnuchin, on his nomination as Treasury Secretary.
"Without Mnuchin key support and assistance, the 'Ab ki bar Trump Sarkar' campaign would not have gotten off the ground. Thanks to what we did together, Trump received a net gain of 1.7 million Hindu votes," Mr Kumar said.
"I am looking forward to rolling up my sleeves and working together with Mr Mnuchin and the other members of the Trump administration to 'Make America Great Again'," he said.
RHC said Mr Mnuchin and Mr Kumar collaborated on Humanity United Against Terror event in New Jersey on October 15, and on other events during the campaign, including a meet and greet between Donald Trump and Hindu leaders in Orlando just days before the election, as well as a visit by Eric Trump to a Hindu Temple.