US First Lady Jill Biden on Sunday visited drought-affected communities in Kenya and appealed for wealthy nations to give more as the Horn of Africa suffers its driest conditions in decades.

Biden concluded her two-nation tour of Africa by calling for a greater spotlight on the record-breaking drought which threatens 22 million people in Kenya, Somalia and Ethiopia with starvation.

The United States has funded the lion's share of the aid budget for the disaster which has killed millions of livestock and destroyed crops.

"We cannot be the only ones. We have to have other countries join us in this global effort to help these people of the region," said Biden at a relief point in Kajiado, a bone-dry county south of Nairobi.

"Unfortunately, you know there is the war in Ukraine. There is the earthquake in Turkey. I mean there are a lot of competing interests but obviously here... people are starving."

Biden heard from parents struggling to feed their children and communities unable to source enough water after five consecutive failed rainy seasons.

The drought was a key focus of Biden's visit to Kenya, with another engagement looking at food security and farming in a changing climate.

But the 71-year-old community college professor also met with women and youth leaders, toured an informal settlement, and laid a wreath for those killed in the 1998 US embassy bombing in Nairobi.

Her visit to Kenya and before that Namibia aims to build on the US-Africa Leaders Summit in Washington late last year where President Joe Biden said his country was "all in" on the hotly courted continent.

Africa has become a renewed diplomatic battleground following Russia's invasion of Ukraine last year and Jill Biden's visit was the first by a senior White House official to the continent since her husband came to power.

In Namibia, Biden said the United States was committed to helping African nations get a louder voice at the UN and other international bodies.