Finance ministers pledged their support for a deal which is aimed at changing international rules by introducing a minimum 15% corporate tax rate.
The agreement thrashed out by the Organisation for Economic Co-operation and Development (OECD) also means online giants can be taxed in countries where they do business, even if they have no physical presence there.
And 132 countries and jurisdictions representing 95% of world GDP have signed up to the deal within the OECD.
Speaking in Venice following two days of G20 meetings, the Chancellor said: “I’m delighted that the full weight of the G20 is behind this historic tax deal – which will make sure our global tax system is fit for purpose in a digital age and crucially is fair.
“We must continue to build on this momentum over the coming months and work together as an international community to create a fairer tax system, which cracks down on tax avoidance and levels up our high street.”
The G20 also reiterated the need for urgent action to tackle climate change and biodiversity loss, and committed to supporting the poorest countries with their response to Covid-19.