Hospital sources said the man who died was among the two critically injured people. The deceased man belonged to Nowshera.
DPO Mardan Faisal Shahzad has confirmed that the attack was a suicide blast.
According to eye-witnesses, the bomber rushed towards the gate of excise office and exploded himself leaving no moment for the guards to retaliate. Security forces shortly arrived at the spot cordoned off the area for investigation.
The injured were moved to Mardan Medical Complex. The identity of the wounded people could not be ascertained as yet.
Pakistan has been battling a homegrown Islamist insurgency since 2004, with groups such as the Pakistani Taliban routinely carrying out attacks as part of their struggle to overthrow the government.
11 injured in Mardan suicide attack by arynews
But militants have still been able to carry out major attacks.
At least 16 people were killed and more than two dozen wounded when a bomb blew up inside a bus in Peshawar in March.