81-year-old president Abdelaziz Bouteflika of Algeria will pursue a fifth term in the elections in April, he reported in a message published by the state media.
Mr Bouteflika has been in office for 20 years, but has rarely been seen in public since he had a stroke in 2013.
He stressed that his "unwavering desire" to serve Algeria allowed him to "transcend the limitations of health problems".
Critics say that this makes it difficult for him to carry out his duties.
He is confined to a wheelchair and has canceled recent official meetings.
The last meeting of Mr Bouteflika with a senior foreign official was during a visit by German Chancellor Angela Merkel in September. An earlier meeting with her was canceled.
Although Mr Bouteflika is expected to win the elections in April, Ahmed Rouaba of the BBC Arabic said.
Is he the oldest world leader?
No, not at all.
The world's oldest elected leader is the 93-year-old Malaysian Prime Minister Mahathir Mohamad.
Mr. Mahathir joked about his own age when he was elected prime minister in May.
"Yes, yes, I'm still alive," he joked to the crowd at a press conference.
Mr. Bouteflika can look closer to home to find another elected president who is considerably older than himself.
The neighbor of Algeria, Tunisia, is led by 92-year-old president Beji Caid Essebsi.