Doreen Bogdan-Martin of United States of America polled 95 votes against Zavazava's 66 to become the director for the telecommunication development bureau (BDT) at ITU.
Nigeria's William Ijeh garnered 16 votes.
The winning candidate will take up the new duties from January 1, 2019, unless otherwise decided by the conference.
In other elections, Houlin Zhao of China was re-elected secretary-general. UK's Malcom Johnson retained the deputy secretary general post while Chaesub Lee was re-elected director Telecommunications Standardisation Bureau.
