Mr Lewis, aged 60, has been in post with the WRU for nine years after joining the governing body as Group Chief Executive in 2006 from his previous post of Managing Director of ITV Wales.
WRU Chairman, Gareth Davies said: “We recognise the massive contribution Roger has made to the growth of Welsh rugby both on the field and off the field and respect his decision to step down after the World Cup which allows us time to find a successor and to build upon Roger’s success.”
Mr Lewis will work closely with the chairman and senior colleagues to help ensure a smooth and effective transition leading up to his departure on 31 October 2015.
The WRU will commence the search for a new Group Chief Executive immediately.
Roger Lewis said: “The time is now right for me to step down after a remarkable period at the helm of the Welsh Rugby Union.
“It has been a fantastic and memorable journey both on and off the pitch and I would like to thank the Board of the WRU for their backing during some challenging times and for my colleagues who have been unstinting in their support for me both personally and professionally.
“After nine years as Group Chief Executive the time is right for me to move forward and by announcing this in advance now, we are ensuring that the transition can be well managed in the best interests of Welsh rugby.
“I am extremely proud of all that we have achieved together over the past nine years. The WRU is now in a strong position to seize the opportunities and face the inevitable challenges of the future and I wish my successor well for the adventure ahead.”
