Knight, who spent 15 years with Audi, replaces Jolyon Nash, who is leaving the BMW-owned luxury car maker at the end of June to "pursue interests outside the company".
Knight, a UK national born in Ireland and brought up in Australia, started his career with BMW’s Australian operation, before joining Volkswagen-owned Audi, where he held a number of senior roles, including general manager for Audi Asia and Pacific.
Rolls-Royce CEO Torsten Müller-Ötvös said: "We are delighted to welcome Fintan Knight to the Rolls-Royce family. His considerable experience provides him with the perfect base to further build and expand on the successes achieved by Rolls-Royce Motor Cars over the past decade.
"Our brand’s global footprint has expanded dramatically over the past few years and the time has come to consolidate and build further business growth on the back of this expansion. Fintan is uniquely positioned to lead our sales and marketing team on this journey."
Last year, Rolls-Royce launched a campaign for its Wraith model to help make the marque "more accessible" to consumers.