England boss Eddie Jones will coach the Barbarians against Fiji at Twickenham in November, just two weeks after the World Cup final.
The game will be the first international match staged in the UK following the World Cup, and is expected to feature some of the stars of the tournament.
"It's a huge honour to be invited to coach the Barbarians," Jones said.
"The club perfectly embodies the values and traditions of the sport."
Jones said 2019 is a "massive year for international rugby" and that he is "looking forward to returning to Twickenham after a successful World Cup campaign to coach a Barbarians team containing some of the stars of the tournament".
Jones is contracted by the RFU until 2021, but will be briefly seconded to the Barbarians before the match with the Fijians on 16 November.
It had been thought Jones would only stay in his role after the World Cup if England reached the semi-finals or beyond.
However, new RFU boss Bill Sweeney recently stated his intention to keep Jones even if England under-perform in Japan.
England's World Cup training camp started earlier this week, with Gloucester fly-half Danny Cipriani among those to be added to the group on Friday.
Jones then names his final World Cup training squad on 4 July, and his final 31-man World Cup party in mid-August.