The Rugby Football League has confirmed the 2020 Coral Challenge Cup final will be played on Saturday, July 18.
It will be the first time in the competition's 123-year history that the final is played in July, which is available as a result of Wembley's extensive involvement in the UEFA Euro 2020 finals in June and July.
The final was traditionally held towards the end of the season in May but, following the advent of Super League, was switched to summer in 2005.
By avoiding the school holidays, the governing body hopes to draw a capacity crowd to Wembley and will put tickets on general sale in October.
RFL chief commercial officer Mark Foster said: "Moving the final to mid-July in 2020 presents us with a real opportunity to attract a capacity crowd for rugby league's showpiece event at Wembley.
"We wanted to give our supporters as much time as possible to plan for that.
"It means that rugby league's big weekend at Wembley will occur on the weekend after the final of the Euros and Wimbledon and the weekend before the opening ceremony of the Olympics, so a fantastic opportunity within the summer of sport next year.
"It will also be at a time when fewer people are away on holiday and, being played during term time, it gives us a great opportunity to work with schools, particularly focusing on the significant number of schools in London that play rugby league."
Saturday's 118th final between St Helens and Warrington will be preceded by the traditional schoolboys curtain-raiser and, for the first time there will be a third match, with Sheffield Eagles facing Widnes in the final of the inaugural AB Sundecks 1895 Cup - a new competition for non-Super League clubs which will take place after the main match.