The accused, Suresh Gautam, killed Pooja in a fit of rage last night after finding her with her lover, Sumit (22), in Baraigarh village, said Kanpur SSP Shalabh Mathur.
Pooja was visiting her relative in Baraigarh where Sumit too was staying, the SSP said, adding, both were residents of Bidhnu and were in a relationship.
At about midnight Gautam came to the house and on finding them together, first killed his daughter and then stabbed Sumit causing serious injuries, he added.
The accused was arrested this morning and during interrogation he confessed to the murder, the SSP added.
Police are still questioning the accused, he said.