Ramnath succeeds Subodh Bhargava whose term as independent director came to an end on March 30.
"I feel honoured and privileged to chair the Tata Communications Board in these exciting times where technology plays such a critical part in defining new business imperatives for enterprises, irrespective of scale or geography," Ramnath said in a statement.
Ramnath has been an independent director of the Tata Communications board since December 2014.
"The company has a very strong value system and business ethos -- values that are intrinsic to the Tata group. The company is on a robust growth trajectory, and I look forward to working with the Board and the management team on building sustainable value for all our stakeholders," Ramnath said.
"Today Multiples is a USD 1 billion Independent Private Equity platform that has the rare distinction of being backed by marquee Indian and global institutions including pension funds, sovereigns and banks," the statement said.
"Having her (Ramnath) as our Chairperson enables us to continue to ensure Tata Communications generates positive impact and delivers value to all our stakeholders including our customers, partners and shareholders," Tata Communications Managing Director and Group CEO Vinod Kumar said.