Parliament's five-year term expired in June but polls were postponed amid concerns over whether the vote could be fair and transparent after a disputed presidential election in 2014.
President Ashraf Ghani last year extended the assembly's mandate until elections were feasible, prompting many to question the legality of his decision.
"Today we announce the date for the parliamentary and district council polls on October 15," election commission chief Ahmad Yousuf Nuristani told reporters.
Nuristani urged the international community to provide funding and support for the election, which will likely be held against the backdrop of a worsening security situation in Afghanistan.
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"We have learnt good lessons from the challenges and problems of the last elections. We are committed to holding (fair and transparent) elections," Nuristani said.
Both Ghani and his rival Abdullah Abdullah, a former anti-Taliban resistance fighter, claimed to have won the fraud-tainted 2014 presidential election, tipping Afghanistan into a crisis that threatened to trigger nationwide unrest.
Nuristani's announcement comes as Kabul hosts a second round of four-country talks aimed at reviving peace negotiations with the Taliban, even as the insurgents wage an unprecedented winter campaign of violence.
NATO-led US troops formally ended their combat mission in 2014, leaving Afghan troops and police to battle an emboldened nationwide Taliban offensive.