The agreement simplifies trade procedures and also makes it easier for the poorest countries to sell their goods by reducing barriers to their exports.
It also gives developing nations more scope to use subsidies to safeguard food supplies.
The first ever trade reform deal on Saturday was approved by all 160 participating countries s whose ministers had gathered on the Indonesian island of Bali to decide on the make-or-break agreement .
The approval came after Cuba gave up on pushing its veto to the package of measures.
"For the first time in our history, the WTO has truly delivered," a tearful WTO chief Roberto Azevedo said.
"This time the entire membership came together. We have put the 'world' back in World Trade Organization," he said.
Food security had been one of the most-hotly debated issues before the agreement was finally clinched.
"It is so agreed," Indonesian Trade Minister Gita Wirjawan said at the Bali meeting, following marathon negotiations between trade ministers from 159 nations that lasted until the early hours of Saturday morning.