Abdul Hadi committed the double murder yesterday in Dera Allayar village of Jaffarabad district in the province, police said today.
Police said Hadi saw his wife with her lover and opened fire at them with an automatic weapon, killing both of them on the spot.
Later, Hadi surrendered to the police with his weapon.
Honour killing is common in conservative Pakistani society where women are seldom allowed to marry of free will or develop relationships.
Last year, 860 women became victim of honour killing in different parts of Pakistan.
In most cases the culprits escaped punishment after being pardoned by complainants who happened to be their close relatives.