Ireland and Afghanistan will join the 10 Test-playing teams in a ranking-based system of qualification for the 2019 World Cup in England and Wales.
The top eight sides in the one-day international rankings on 30 September 2017 will automatically qualify.
The bottom four in that table will then play in a 10-team World Cup Qualifier in 2018, which will determine the final two teams for the tournament.
As a result, Ireland will no longer play in the World Cricket League (WCL).
The WCL is the International Cricket Council's (ICC) one-day competition for its leading associate and affiliate members.
The next WCL will run over two years from the summer of 2015 and feature Hong Kong, Namibia, Netherlands, Papua New Guinea, Scotland, the United Arab Emirates, Kenya and Nepal - with the leading sides bidding for places in the World Cup Qualifier.
The winners of a play-off between the WCL champion and the lowest team in the ICC rankings table will then be included in the rankings for the next cycle, with the loser dropping into the WCL.
Ireland and Afghanistan will still compete in the first-class Intercontinental Cup 2015-17, which involves four-day matches, along with Hong Kong, Namibia, Netherlands, Papua New Guinea, Scotland and the UAE.
|ICC ODI rankings (as of 27 January 2015)|
|1. Australia||120||7. Pakistan||97|
|2. India||115||8. West Indies||95|
|3. South Africa||112||9. Bangladesh||75|
|4. Sri Lanka||107||10. Zimbabwe||53|
|5. England||104||11. Afghanistan||41|
|6. New Zealand||102||12. Ireland||34|
"Both Afghanistan and Ireland have excelled on and off the field in recent years, and this decision is a critical step forward to the ICC's aim of having more competitive teams in international cricket," said ICC chief executive David Richardson.
"The decision also provides even greater context to one-day international cricket, and provides a fully meritocratic pathway into Cricket World Cup and Champions Trophy events.
"It also compliments the recent decision by the ICC board to introduce opportunities for associate and affiliate members to play Test cricket through the ICC."
Cricket Ireland CEO Warren Deutrom commented: "We are absolutely delighted with the opportunity to qualify directly to the World Cup.
"Ireland has worked very hard over recent years to prove itself as the leading associate side and has beaten a number of full members over the years.
"We are confident that we can now accelerate our progress as part of this qualification structure with the full members, while this is also an excellent boost as we put our finishing touches on our preparations for the World Cup 2015."