The move comes amid pressure to avoid a repeat of last year's fraud-tainted presidential vote.
President Hamid Karzai's spokesman said Saturday the president has notified the United Nations of his decision.
Last month, Karzai signed a decree allowing him to appoint all five members of the Electoral Complaints Commission for the September polls. The body previously had three U.N. appointees.
The decree was criticized as a bid to control the body, which stripped Karzai of nearly one-third of his votes last year. Karzai was declared the victor after his challenger dropped out of a runoff.