The top four leagues in Europe will be given four guaranteed places in the Champions League group stage from the 2018-19 season.
The four highest-ranked associations in the coefficient table - currently Spain, Germany, England and Italy - will no longer have to send teams into the qualifying rounds or play-off phase to reach the competition proper.
UEFA has confirmed the change will be introduced in two years, as part of its reformatting of European club football's top competition.
The club coefficient system will also undergo changes. Historical success in the competition will now be acknowledged in calculating a club's coefficient points, with weighting in favour of Champions League and Europa League titles.
The association coefficient, which determines the ranking of countries in the access list, will remain unchanged.
Distribution of revenue for clubs will be "increased significantly", UEFA has said, with a new four-pillar system set to better reward performance in the competition, while market pool shares will decrease.
A subsidiary company, the UEFA Club Competitions SA, is to be created to manage UEFA's club competitions.
The new regulations were announced at a UEFA media conference in Monaco, shortly before the draw for the Europa League group stage.
Speaking about the amendments, UEFA General Secretary ad interim Theodore Theodoridis said: "The evolution of UEFA's club competitions is the result of a wide-ranging consultative process involving all stakeholders and taking into account a wide range of expertise and perspectives.
"The amendments made will continue to ensure qualification based on sporting merit, and the right of all associations and their clubs to compete in Europe's elite club competitions.
"We are happy that European football remains united behind the concepts of solidarity, fair competition, fair distribution and good governance."