This was signed off on by the ICC Board in London on Thursday, during the ICC's AGM.
Ireland and Afghanistan are included into the elite group that is permitted to play in the traditional five-day Test matches.
Afghanistan Cricket Board Chief Executive Shafiq Stanikzai said, "For a nation like Afghanistan, it is a huge and remarkable achievement, the entire nation will be celebrating across all five regions and different provinces, it is the perfect Eid gift."
"Everyone has waited for this news and has been so keen to hear this news. Afghanistan Cricket has gone from strength to strength and we dared to dream that this would happen and today it has become a reality."
Stanikzai thanked the ICC Board members for their support.
“I would like to thank the ICC and the Board who have demonstrated today that they are committed to growing the global game and rewarding nations who are performing on and off the field. As an administrator, every achievement is huge and it opens the doors to new challenges and we need to work hard to maintain and sustain our development at the top of the cricket world."
Cricket Ireland Chief Executive Warren Deutrom was equally ecstatic.
"We are delighted and proud with today's historic announcement. It is an extraordinary testament to the talent and endeavour of thousands of passionate players, coaches, volunteers, staff, clubs and committee people."
ICC Chief Executive David Richardson said, "I would like to congratulate Afghanistan and Ireland on their Full Membership status which is the result of their dedication to improving performance both off and on the field resulting in the significant development and growth of cricket in their respective countries."
"Both have clearly demonstrated they meet the new criteria and as such have made the progression to Full Membership."
Until 1982 there were only seven Test-playing nations but that year Sri Lanka were admitted, Zimbabwe then joined in 1992 and Bangladesh became the most recent member in 2000.
Cricket has a long history in Afghanistan but the country played amongst the sports minnows until gaining one-day international (ODI) status in 2011.
Two years later the country, still suffering from the impact of war and conflict, was given 'associate member' status of the world governing body ICC.
In 2015 Afghanistan played in their first 50-over World Cup and they have also featured in the World Twenty20 competition.
Ireland have steadily progressed in the game and first qualified for the World Cup in 2007 when they pulled off a shock win over Pakistan and they have qualified for both World Cups since.
Image: Two young Afghanistan fans watch the ICC World Cricket League Division One match in 2012.
Photographs: Getty Images
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