The RFL has reached an agreement with the NFL side that will allow McNamara to continue as coach of the national side in a part-time capacity.
RFL chief executive Nigel Wood said in a statement on the organisation's website: "It gives me great pleasure to confirm that Steve has agreed to continue as England coach into 2014 when we will be looking to build on the advances seen over the last four years.
"The systems and structures that have been put in place during Steve's tenure as England coach have put Rugby League in this country in a good place and this move will ensure that we continue to make progress.
"Steve can also realise his own desire to return to club coaching and I am sure his involvement with Sydney Roosters will have a positive impact on his own career development."
McNamara will work alongside former Catalans Dragons coach Trent Robinson at the club.