“This new arrangement allows me to keep doing the thing that I’m passionate about, coaching and mentoring players, while also balancing other commitments which are important to me.”
Sinfield’s new contract reportedly commits him to England until the next Rugby World Cup in Australia in 2027.
England head coach Borthwick said: “The work he does on and off the field is invaluable to our players, so I am pleased he’ll remain part of the management team and continue to contribute towards the success of England rugby.”
Sinfield initially worked as England’s defence coach, but moved out of the post and made way for Felix Jones after the 2023 World Cup.
Oyonnax head coach Joe El-Abd was recruited to fill the defence coach vacancy after Jones’ abrupt departure earlier this year.
Sinfield has raised more than £10m for research into Motor Neurone Disease in honour of his former team-mate Rob Burrow, who died in June.
His latest fundraising challenge will involve running more than 50km every day for a week and will begin later this year.