Union members had raised concerns about unequal pay among the technical staff employed by the ENO.
The predominantly female workers in the costume, wardrobe and wigs departments found they were being paid less than colleagues in other technical roles like props, sound and lighting departments.
A detailed job evaluation study and pay audit showed that many jobs, mostly undertaken by women, had been historically undervalued. The union said this was a classic case of equal pay for work of equal value.
As a result, all salaries in costume, wardrobes and wigs were brought into line with those in other technical departments.
Karen Hopkinson, chair of the ENO union branch, said: “It is incredible that we have broken through the first barrier of gender pay equality within theatre. But this is only the first hurdle and the ENO is the first company to right a historic wrong.
“I would encourage all of my colleagues within costume, wardrobe, wigs and make-up to feel empowered by this outcome,” Karen added.
Helen Ryan, arts and entertainment assistant national secretary at BECTU, said: “We are pleased that ENO has shown great leadership and listened to BECTU members to effectively tackle the gender pay disparity.”