It was claimed Norbert Chikerema carried out the horrific killing after convincing himself his wife was having an affair.
West Midlands Police officers found Chikerema behind the wheel of his Nissan Qashqai in a supermarket car park in the early hours of January 30.
Beside him in the passenger seat was his wife Nyasha Kahari − known to family and friends as Gillian.
Officers found she had suffered catastrophic head injuries.
She was pronounced dead at the scene, say West Midlands Police.
Mother-of-four Mrs Kahari had left the family home in Overdale Road, Quinton, with her husband the previous evening.
It was thought they were heading out on home visits as part of their care in the community business.
However, detectives suspect 42-year-old Chikerema had already planned to kill his wife that night.
A blood-stained axe was found inside the car when officers traced it to Lidl supermarket in Mackadown Lane, Tile Cross.
Chikerema confessed to killing the 35-year-old but claimed he was not of sound mind at the time and denied murder.
But he was found guilty of murder following a trial at Birmingham Crown Court on Tuesday.
West Midlands Police Detective Inspector Paul Joyce, from Force CID, said: "Chikerema’s actions mean four children now have to live without their mother; a family has been tragically ripped apart and he will have to live with the consequences of his brutal attack forever.
“He suggested he was not of sound mind at the time of the killing and pleaded not guilty on the grounds of diminished responsibility.
“However, we demonstrated a degree of advanced planning − notably taking the axe out in the car that night − and the jury quickly found him guilty.
“We found him alongside his dead wife early on the morning of 30 January but it is not clear exactly where or when he killed his wife…only he knows that.
“Our thoughts remain with the children and wider family and we wish them all the best for their futures."
A tribute released on behalf of Ms Kahari’s family read: “Gillian was a decent, loving mother of four children, two boys and two girls. She was a caring and hardworking woman who always strived to keep her family happy.
“Gillian will be missed by her family and all those who knew her."
He will be sentenced on Wednesday.