British, Commonwealth and WBO European champion Walsh, 30, is unbeaten in his 21 professional fights.
The Norfolk boxer defeated Andrey Klimov on points in October to become the mandatory challenger for American Davis' belt.
Davis, 22, is also unbeaten, having won 16 of his 17 bouts by knockout.
He stopped Jose Pedraza in the seventh round in New York in January to win the title.
The fight against Walsh was confirmed on Tuesday at a press conference in London, attended by Davis' promoter, five-division world champion Floyd Mayweather Jr.
Liam Walsh will challenge champion Gervonta Davis for the IBF super-featherweight world title on Saturday, 20 May at London's Copperbox Arena.