Planting spree, which officials say is a world record, is part of a campaign to fight deforestation and climate change.
Ethiopians have planted more than 350 million trees in a single day as part of a campaign to fight deforestation and climate change.
Getahun Mekuria, Ethiopia's minister of innovation and technology, said 353,633,660 seedlings were planted in 12 hours on Monday.
The planting spree, which surpassed the initial goal of 200 million trees planted in one day, will be a world record, officials said.
Prime Minister Abiy Ahmed's ambitious Green Legacy Initiative, launched in May, aims to plant four billion trees across Ethiopia by October.
"Today, Ethiopia is set in our attempt to break the world record together for a green legacy," Abiy's office said in a Twitter post on Monday.
Some schools and government offices were closed for the occasion and Abiy told fellow Ethiopians to "go out and make your mark", as he planted his own tree in the southern city of Arba Minch.