Officials say the attackers ambushed Gen Dostum’s convoy in Balkh Province.
The Taliban said they carried out the attack, which lasted an hour and left two other bodyguards injured.
It is the second attempt on Gen Dostum’s life since the ethnic Uzbek and former warlord returned from self-imposed exile last July.
That month, 14 people died in a suicide bombing at Kabul airport shortly after his arrival. Islamic state says it carried out that attack.
Gen Dostum joined Afghanistan’s unity government in 2014 and is a controversial political figure.
He helped the US oust the Taliban in 2001 but has been blamed for some of the worst atrocities in the country’s long-running civil war.
More than a year ago, he left for Turkey after being accused of ordering his men to kidnap and rape a political rival. He has denied the accusations and insists his travel to Turkey was for a medical check-up.
Gen Dostum’s reappearance was preceded by unrest in his northern powerbase, as supporters demanded his return and the release of a militia leader.
Analysts believe President Ashraf Ghani sanctioned his return to try to shore up support among Uzbeks ahead of presidential election scheduled for 28 September.