The nation had left after the bloc recognised Western Sahara as a sovereign territory in 1984.
Morocco rejoined the club of African states on January 31, 33 years after quitting over the recognition of Western Sahara. The move brings one of Africa's largest economies into the fold and raises hopes of a softening of one of its thorniest territorial disputes – Morocco considered Western Sahara as part of its territories.
Capping a year-long charm offensive that mirrored a broader investment push into Africa, Morocco's King Mohammed VI was cheered as he took his seat for the first time in the Addis Ababa headquarters of the 55-nation African Union (AU). Rabat left the AU's predecessor, the Organisation of African Unity, in 1984 in anger at its acceptance of the phosphate-rich Western Sahara as a full-blown member.
"We have never broken up the ties or severed the ties, the ties have always been there and you could rely on us. The strong bilateral relations have been developed in a significant manner," King Mohammed VI said.
African support for Western Sahara has ebbed as the importance of Morocco's $110 billion economy, Africa's fifth largest, as a trade and investment partner has grown.
At an AU summit this week, Morocco was re-admitted to the fold, with 39 countries expressing support and only 10, believed to be led by Algeria and South Africa, expressing reservations.
For Morocco, a relatively liberalised economy and firm Western ally, readmission to the AU should smooth its entry into fast-growing African economies to the south and help reduce its reliance on stagnant European markets to the north.
Adama Gaye, who is the Chairman of Newforce Africa, talks to TRT World.
The independence movement
Morocco claimed the territory of Western Sahara, which has been contested since Spanish colonial powers left in 1975 and fought a 16-year war with the Polisario independence movement, that established the self-declared Sahrawi Arab Democratic Republic with support initially from Algeria and then from across Africa.
Since a 1991 ceasefire, UN peacekeepers monitor the Moroccan forces in what Rabat calls its southern provinces and guerrillas in the Polisario-controlled area bordering Algeria.
UN-backed attempts to hold a referendum on self-determination have been deadlocked since 1991 and Rabat has presented its own autonomy plan.
Sahrawi foreign minister Salem Ould Salek described the AU's admission of Morocco as a 'major step' towards full international recognition since it would now be in the same room, on equal terms, with its rival.
The return to the AU comes at a sensitive time.
Last year, Morocco expelled some UN staff from Western Sahara after then-UN chief Ban Ki-Moon visited Sahrawi refugee camps in southern Algeria.