Moves to guarantee women about 40 per cent of business leadership roles in Spain were put forward on the eve of International Women's Day.
The bill represents an "important step towards equality" and includes Spain's decision-making bodies, said Nadia Calvino, Deputy Prime Minister and Economy Minister.
It was unveiled on Tuesday but it is not clear that the government has enough support to push it into law before a general election later this year.
The legislation would introduce a 40 per cent threshold for women serving on the boards of stock exchange listed companies, those with more than 250 employees, or yearly earnings of at least €50 million.
Measures to promote female participation in politics are also in the bill.
Several European countries, including Norway and France, already have a similar threshold in place in line with a European Parliament ambition to increase the number of women on corporate boards by 2026.
Spain's government is a leader in gender parity, with women holding 63 per cent of ministerial roles, one of the world's highest proportions.
Prime Minister Pedro Sanchez's cabinet includes 14 women and eight men.
Spain has a benchmark for women's rights in Europe, notably after its 2004 adoption of a law promoting measures against gender-based violence.
Last month, Spain's parliament approved a law granting paid medical leave to women suffering severe period pain, becoming the first European country to advance such legislation.
International Women's Day is an annual celebration of the efforts made by campaigners championing gender equality over the decades — but it also serves as a rallying cry to the world on the progress still to be made.
UN Secretary General Antonio Guterres said on Monday that progress on women’s rights was “vanishing before our eyes".
Mr Guterres told the opening session of the Commission on the Status of Women, the UN’s largest gathering on women’s empowerment, that "gender equality is growing more distant".
"On the current track, the UN Women puts it 300 years away," he said.
“Women's rights are being abused, threatened and violated around the world."
The pace of legal reforms concerning the equal treatment of women around the world has also plummeted to a 20-year low, posing a potential threat to sustainable and inclusive growth at a critical time for the world economy.