The mother, named as Emine A., found out that her daughter Meryem A. was pregnant during a visit to neighbours, the Hurriyet daily reported.
She then went back home to find a gun and returned to shoot her daughter — who worked as a cashier in a market — five times, it said.
Bystanders outside the apartment block in the Selcuk district of the southern city of Nigde rushed to help and took Meryem to hospital but she died on the way.
The mother was detained by police but then had a nervous collapse and was hospitalised. The investigation is continuing.
Turkish authorities acknowledge there is a grave problem of violence against women in the country, although the vast majority of cases involving attacks perpetrated by men.
According to the non-governmental Platform to Stop Violence Against Women, 286 women were murdered in Turkey in 2014 and 134 so far in 2015. -AFP