"It will help provide life-saving support to refugees, asylum seekers, and others impacted by conflict and food insecurity in the region," Blinken said in a statement about the new aid, which will go to Niger, Burkina Faso, Chad, Mali and Mauritania as well as Sahelian refugees in Libya.
Landlocked Niger and its neighbors are all struggling to repel Islamist insurgents who have killed thousands of people, displaced millions more and in some cases seized control of vast swathes of territory.
Groups linked to al Qaeda and Islamic State have carried out dozens of attacks in southwestern Niger, including some in which dozens of Nigerien soldiers were killed, but the violence has not spread across the whole country as it has done elsewhere.
Shortly after landing in the capital Niamey, Blinken met with people involved in a program, partly funded by the U.S., to disarm and rehabilitate defectors from extremist groups.
"They're making the right choices, we think, to help deal with the kind of threats that are common across the Sahel. So, we're trying to highlight a positive example," a senior State Department official told reporters.
The official praised Niger's President Mohamed Bazoum for speaking out against Russia's private Wagner group of mercenaries, which has been hired by Mali's junta to help fight insurgents there. Mali describes the Wagner personnel on its territory as "trainers".
Blinken said the use of Russian mercenaries had not proven an effective response to insecurity.
"It's not just we know this is going to end badly, we've already seen it end badly in a number of places," Blinken said.
Speaking to AFP on the highest-level visit ever by a US official to Niger, Blinken called for moving on from what was often seen as a military-first approach by the United States and former colonial power France, which wound up a controversial nine-year operation in Mali in November.
"We're in the midst of building something relatively new," Blinken said in an interview late Thursday in the capital Niamey.
"We absolutely have to have a holistic, comprehensive approach in which security is absolutely necessary but is not enough."
"The fact that Niger, which is obviously one of the poorest countries on earth, is doing this so effectively, I think only underscores the importance of taking this comprehensive approach."
Blinken traveled to Niger from Ethiopia, where he met on Wednesday with Prime Minister Abiy Ahmed and other government figures in an effort to repair the diplomatic damage caused by the two-year war in Tigray that ended in November.
Blinken's trip is the latest in a series of visits to Africa by U.S. government figures as Washington seeks to boost ties with a continent where China's influence is strong and many countries maintain cordial relations with Russia.
His visit to Niger is the first by a U.S. Secretary of State.
This report uses data from Reuters and Agence France-Presse.