Nigeria’s quartet of Johnson Nnamani, Imaobong Nse Uko, Opeyemi Oke and Bamidele Ajayi combined to clock 3:19.70 in the mixed 4x400m relay.
It was their second championship record in as many races, having run 3:21.66 earlier in the day.
They also made history by becoming the first ever champions in the event which was making its debut at a World U20 Championships.
The medal is also Nigeria’s first world U20 gold since 2008 when Folashade Abugan won the women’s 400m title in Bydgoszcz.
Godson Brume, younger brother to Olympic medalist, Ese Brume, was the man to beat in heat three of the men’s 100m as he returned a time of 10.22 adm finished first.