Land border controls will however remain in place due to Austria's opposition to the eastern European countries becoming full members of the Schengen zone for fear of an influx of asylum seekers.
Despite the partial membership, the lifting of controls at the two countries' air and sea borders is of significant symbolic value.
Admission to Schengen is an "important milestone" for Bulgaria and Romania, symbolising a "question of dignity, of belonging to the European Union," according to foreign policy analyst Stefan Popescu.
"Any Romanian who had to walk down a lane separate from other European citizens felt being treated differently," he told AFP.
Ivan Petrov, a 35-year-old Bulgarian marketing executive who lives in France, said he was enthusiastic about less stressful travelling and the time he would be able to save.
"This is a great success for both countries. And a historic moment for the Schengen area -- the largest area of free movement in the world. Together, we are building a stronger, more united Europe for all our citizens," EU chief Ursula von der Leyen said in a statement on Saturday.
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