McNulty, who is planning to move to Singapore in early 2014, will leave Excel London on 20 December after five years at the venue.
Following her move, McNulty plans to explore opportunities in Singapore's business tourism market.
She said: "The time has come to embrace an exciting new opportunity and I am thrilled at the prospect of a challenge overseas.
"I have loved working at Excel and I will be sad to leave, especially having worked with such a talented and committed team of amazing people. We have met and exceeded our targets and I can't imagine a better team to work with."
As a result of McNulty's departure, Excel London will recruit a new corporate business development manager and Jamie Ades, who joined in May 2013, will move his focus from the corporate sector to the association market at the beginning of December.