Prime Minister David Cameron says he will campaign with his "heart and soul" to remain in the EU after agreeing a deal on his reform proposals.
After two days of negotiating, Mr Cameron said the deal gives the UK "special status" in the EU.
The deal sees the UK able to limit benefits for migrants and removes the country from the treaty for an 'ever-closer' Union.
The 'emergency brake' system will see the UK able to halt migrant benefits for four years when they are exceptional levels of migration - the brake can be applied for a seven-year period. The amount of child benefits paid to EU migrants, whose children live abroad, will now be calculated on the cost of living in that country, rather than the UKs.
The treaty changes on the ever-closer EU mean the UK "can never be forced into political integration". Finally, the deal sees the UK able to introduce "an emergency safeguard" for its financial sector in the City, ensuring British businesses are not unfairly discriminated for being outside of the eurozone.
Following a cabinet meeting back in the UK, the referendum was set for 23 June.
"We should be suspicious of those who claim that leaving Europe is an automatic fast-track to a land of milk and honey," Mr Cameron said.
"The British people must now decide whether to stay in this reformed European Union or to leave. This will be a once-in-a-generation moment to shape the destiny of our country."
European Council President Donald Tusk said the deal was agreed unanimously by all Member States. He said: "We didn't walk away from the negotiating table. We were willing to sacrifice part of our interests for the common good, to show our unity.
"I deeply believe the UK needs Europe and Europe needs the UK. But the final decision is in the hands of the British people."