ODM party leaders Raila Odinga and Hassan Joho left the country on Friday for Accra Ghana.
The two flew out of the country on official invitation from the Ghanian government to attend the swearing-in ceremony for President-elect Nana Akufo-Addo.
"I departed for Accra early today (Friday) morning accompanied by my Deputy Hassan Ali Joho to attend the inauguration of President-Elect Nana Akufo-Addo," Raila posted on his official Facebook page.
"I congratulate incumbent President John Dramani Mahama for his adherence to democratic principles and providing leadership not just to Ghanaians but to the continent at large. His gracious hand over is an example to all on the sovereignty of the will of the people."
Nana defeated first time President Mahama in a hotly contested presidential election in December 2016.
The international community lauded the democratic principles instilled by the West African country after an incumbent accepted defeat.
This is uncommon in Africa.