NUS president Megan Dunn told delegates that their voices were "too powerful" to be ignored during the upcoming referendum.
The EU is a force for "tolerance and respect", she told the conference, which will later debate claims that the NUS itself is institutionally racist.
A motion submitted to the conference's welfare zone states that a probe into racism within the union should be broadened to investigate claims of anti-Semitism.
Around 800 delegates and 300 observers from affiliated colleges and universities are attending the three-day conference in the Sussex seaside town.
Speeches opening the event from Dunn, the Trade Union Congress' Frances O'Grady and Stronger In campaigner June Sarpong all highlighted the benefits of the EU to Britain's students.
“The student voice is too powerful to be ignored in this referendum”
Megan Dunn, NUS national president, said: "This is a forward-thinking city that looks out to the continent and is the perfect setting for this conference as we edge ever closer to the European Referendum.
"The student voice is too powerful to be ignored in this referendum.
"We travel, work, and study abroad to a greater degree than previous generations while politically we are involved in pushing for innovation in climate change, international development and global justice.
"The EU advances and protects the values that Britain’s young people believe in and is a force for tolerance and respect."
“Jobs, growth and rights at work will be at stake.”
Frances O’Grady, TUC general secretary, said: "Britain’s students face huge debts, expensive housing and an uncertain future in our insecure labour market.
"It’s crucial they make their voices heard during the EU referendum, when jobs, growth and rights at work will be at stake.
"The latter may not matter much to the likes of Nigel Farage, but if you’re working in a bar or supermarket on low pay while you’re studying, those rights are worth voting for."
“Young people have more to lose with a vote to leave”
June Sarpong, TV presenter and Stronger In board member, said: "I’m delighted to have been invited to speak at the NUS conference.
"It’s vital young people are engaged in the debate about the future of our country.
"Whether it’s jobs, prices or the opportunity to travel, study or work abroad, we’re stronger inside the EU.
"Young people have more to lose with a vote to leave – and more to gain from staying – than any of us.
"Their voices and views must be heard."
Yet Matthew Elliott, Chief Executive of Vote Leave said: "The EU is neither progressive nor forward looking.
"Its policies have harmed the prospects of a generation on the continent, and it is young people who can least afford to foot the bill for the £350 million we hand to Brussels every week.
"Outside of the EU we will still trade and travel across Europe, it’s a shame that the NUS is unwilling to engage in an honest debate."