The charity found itself at the centre of a scandal when it emerged some of its workers used prostitutes there.
Mark Goldring will stand down as Chief Executive at the end of this year.
He said "the time is coming for a new leader" and after the "very public exposure of Oxfam's past failings, we have redoubled our efforts to ensure that Oxfam is a safe and respectful place for all who have contact with us".
The charity became embroiled in a scandal following allegations of sexual misconduct against some of its workers in Haiti.
It was made aware of allegations that some of its aid workers used prostitutes while they were working in the relief effort there, following a devastating earthquake in 2010.
Mark Goldring added: "What is important in 2019 and beyond is that Oxfam rebuilds and renews in a way that is most relevant for the future and so continues to help as many people as possible around the world build better lives,"
He has held the position since 2013 and is due to stay on until a successor is found.
Caroline Thomson, Chair of Oxfam, said: "It is with great sadness and with thanks for his dedication and leadership that I accepted Mark's decision to stand down."