Kagame has been president since 2000 although he has been effectively in control since his rebel force marched into Kigali in 1994 to end a genocide.
At a meeting of top officials of the ruling Rwandan Patriotic Front, RPF, in the capital Kagame was endorsed by 99.1% of votes cast.
"We know where this country has come from, I appreciate the apparent role you have played in that. I also appreciate the trust that you always and continue to place in me," Kagame said after he was endorsed.
"The burden you have given me I have accepted to carry."
Voters will elect their next leader for a five-year term on July 15. They will also be electing their lawmakers.
At the last election in August 2017 Kagame won his current seven-year term with 98.63% of the vote, according to the electoral commission.
In 2015 Rwanda changed its constitution, meaning Kagame is now only eligible to seek a maximum of two five-year terms after the current one ends this year.
He has drawn international applause for presiding over peace and economic growth since the end of the 1994 genocide, in which about 800,000 ethnic Tutsis and moderate Hutus were killed.
But he has also faced mounting criticism for what human rights groups say are the suppression of political opposition and the muzzling of independent media.
In the July vote, he is widely expected to face Frank Habineza from the Green Party among other opposition candidates.
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