The Labour leader made the admission as he took audience questions during a BBC Question Time special on Friday evening.
It comes despite Labour's official Brexit position being to negotiate a new deal that would then be put to the British people in a referendum.
The party would then decide at a special conference whether to campaign for or against their own deal.
An audience member asked: “Will you campaign to remain or leave the EU if elected. Why would anyone vote Labour without knowing the answer to that question?”
Mr Corbyn replied: “One, we will negotiate a credible Leave deal with the European Union,” at which point the audience started laughing.
He continued: “I’m trying to answer the gentleman’s question. Secondly, we will put that alongside Remain in a referendum.
“My role and the role of our government will be to ensure that that referendum is held in a fair atmosphere and we will abide by the result of it.
“And I will adopt, as prime minister, if I am at the time, a neutral stance so that I can credibly carry out the results of that to bring communities and country together rather than continuing an endless debate about the EU and Brexit.”
Closing the debate, host Fiona Bruce asked: “And just to be clear, in a yes or no answer, you are telling us tonight that you will… remain neutral on the issue of whether or not we should remain within the EU?”
Mr Corbyn replied: “Yes,” adding: “First heard here on Question Time.”