Asian powerhouse China has had a stranglehold on the sport, winning 24 of the 28 gold medals at the Olympics since table tennis was introduced at the 1988 Games. China swept all four titles at the last two Olympics in London and Beijing.
Besides the decision to allow the mixed-nation pairs, the basic quota of singles players per country will also be reduced from five to three in future world championships, the International Table Tennis Federation (ITTF) said.
"With open discussion and with the interest of our sport in mind we made some memorable decisions that will definitely enhance our World Championships in the future," ITTF president said Adham Sharara in a statement.
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However, the rule to increase the quota if a country has a player in the world's top 100 and one more if they have a player in the top 20, making a maximum of five, remains valid.
In the men's game, Chinese players have won seven of the past eight biennial world championships, while China's women have claimed the last 10 titles.
The semi-finalists in men's and women's singles at the last world championships in Paris were all Chinese.
Tokyo is currently hosting the World Team Table Tennis Championships while Kuala Lumpur will hold the event in 2016. Suzhou in China will host the individual world championships next year.
Tokyo 2020 - China vs Germany - Table Tennis Men's Team Gold Medal - Olympic Highlights
Tokyo 2020 - Japan vs Republic of Korea - Table Tennis Men's Team - Olympic Highlights