US First Lady Jill Biden arrived in Kenya on Friday, kicking off a visit aimed at focusing attention on the worst drought to hit the Horn of Africa in decades.

Five straight seasons of poor rainfall have killed millions of livestock, destroyed crops and left some 22 million people at risk of hunger in Ethiopia, Kenya and Somalia, with a sixth season also forecast to fail.

Biden travelled to Kenya from Namibia, part of a two-nation tour aimed at deepening ties with the continent, which has become a renewed diplomatic battleground following Russia's invasion of Ukraine last year.

The first senior White House official to travel to the region since her husband President Joe Biden came to power, the 71-year-old community college professor's visit will also focus on the empowerment of women and youth.

The tour aims to build on the US-Africa Leaders Summit in Washington late last year where President Biden said his country was "all in" on the hotly courted continent.

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

"We're committed to making sure that African countries not only have a voice in organisations like the UN Security Council and G20, but that those voices are valued as equal partners," Biden said at a luncheon in Windhoek on Thursday.

This is Biden's first trip to Africa as the first lady of the United States.