She will become semi-retired, and will not continue with her role as chair of the Meetings Industry Association (MIA) Destinations Group.
O'Reilly will be replaced at Liverpool Convention Bureau by Kate Currie, who has been working at the body for four years and will take the role of interim convention bureau manager.
"Having been with Liverpool Convention Bureau for a number of years I have been privileged to see the city develop into a leading destination, win many accolades and add many hotels and venues to its portfolio," said O'Reilly. "I feel the time is right for me to move on and know that Kate will continue to be a valuable asset to the bureau and the city."
A replacement for the MIA role is yet to be announced.
O'Reilly joined the destination team in 2007 and played an instrumental role in helping to set up the Liverpool Convention Bureau in 2009, relocating to Liverpool to fulfil the role.
Kate Currie is currently conference manager at the bureau and said O'Reilly had been a "real force for positive change within the bureau".
"I look forward to carrying forward her influence," she added. "The next few months will be an exciting time for the city with many new developments and investments set to take place and I look forward to my new role within this."