The 41-year-old succeeds the Reverend Doug Birdsall, who starts his new role as president of the American Bible Society in March.
Dr Oh is founder and president of Christ Bible Seminary in Nagoya, Japan, where he is passionate about raising up a new generation of Christians committed to the spread of Christianity in the country.
The Korean-American has been involved in the Lausanne Movement since 2004 and has been a member of the Lausanne Board since 2007.
He will take up his new post as Lausanne chief executive on 1 March before being formally installed at the Lausanne Global Leadership Forum in South Asia in June.
His appointment was welcomed by Ram Gidoomal, chair of the Lausanne Movement Board of Directors.
"Michael is a cross-cultural bridge-builder, from East to West and across generations. He knows the overall Movement well and understands the complexity of this leadership calling," he said.
"He will be able to build on the firm foundation that Doug Birdsall and the global leadership of Lausanne have established, to the glory of God."
After passing the baton of leadership to Dr Oh, Rev Birdsall will continue to serve in leadership with Lausanne as an Honorary Chair.
Rev Birdsall praised his successor, saying Dr Oh had demonstrated the ability to inspire and enlist a new generation around the globe who share Lausanne's commitment to the vision of "the whole church taking the whole gospel to the whole world".
"Michael is an exceptionally gifted younger leader who will serve the Movement with vision and passion in the years to come," Birdsall said. "As a reflective practitioner, he embodies the essence of the 'spirit' of Lausanne – humility, friendship, study, prayer, partnership and hope."
"Lausanne is in good hands, and the future is filled with promise."
Dr Oh will continue to live in Japan while serving Lausanne.
He said: "I am humbled by this appointment as I follow in the footsteps of the legacy that God started in the Movement through godly leaders like Billy Graham, Leighton Ford, Gottfried Osei-Mensah, Paul Cedar, and my predecessor, and friend, Doug Birdsall.
"My own development as a leader, along with countless other younger leaders within Lausanne, has been significantly impacted by the mentorship of Doug, the Lausanne Board, and other Lausanne leaders.
"Lausanne is getting younger, stronger, and more representative of the rich diversity and depth of the global church.
"Mobilising and connecting global younger leaders for world evangelisation will be a great joy and priority as I take the leadership of Lausanne."