Patel, who joined Tulchan in 2008 after a 15-year career in investment banking, will start at TalkTalk in mid-November.
He replaces current investor relations director David Boyd, who is understood to be leaving TalkTalk to pursue other opportunities.
Before moving into financial PR, Patel held senior positions at HSBC, Merrill Lynch Europe and NM Rothschild & Sons. At Tulchan, Patel worked on accounts including Legal & General, New Look and Enterprise Inns.
Andrew Grant, founder of Tulchan, said: 'We have enjoyed working with Mal and he has all the skills to make this new role at TalkTalk a success. He leaves with all of our best wishes.'