Paul Butler will attempt to become a two-weight world champion when he faces South African Zolani Tete for the IBF super-flyweight crown in March.
The undefeated fighter, 26, won the IBF Bantamweight title in June but vacated the belt to drop a weight class.
He would become the first Briton in over 100 years to win a second world title at a lower weight.
Meanwhile, WBO middleweight champion Andy Lee and Billy Joe Saunders have been ordered to negotiate a contest.
Lee, 30, claimed his title with the surprise stoppage of Russia's Matt Korobov on 13 December but Saunders - undefeated after beating Chris Eubank Jnr in November - is mandatory challenger.
In a statement, the World Boxing Organisation said the pair had "30 days" from the date of Lee's win to negotiate an agreement for a bout.
Any agreement would likely set a date after Butler's 6 March meeting with Tete at Liverpool's Echo Arena , who claimed the vacant IBF super-flyweight crown in July.
Tete, 26, has three defeats in 22 matches and claimed the vacant IBF super-flyweight crown in July, but has never fought in the UK.
Butler, of Ellesmere Port, beat compatriot Stuart Hall to win his first world title and has not tasted defeat in 17 outings, winning eight times inside the distance.
Meanwhile, Eubank Jnr will take on interim WBA World Middleweight champion Dmitry Chudinov at the O2 arena in London on 28 February, on the undercard of Tyson Fury's WBO International Heavyweight title defence against Christian Hammer.