The couple, who were married two weeks ago, were apparently returning from a dinner in Somerset West, when two armed men approached their shuttle service bus in Gugulethu, Tammy Evans, spokesperson for MEC Alan Winde, told Sapa.
Western Cape police spokesperson Lieutenant Colonel André Traut said the hijacking happened at the intersection of NY108 and NY112 around 23:00 on Saturday. Two armed men forced the driver out of the vehicle and drove off with the couple.
Around midnight they dropped the 31-year-old man off in the Harare area of the Khayelitsha informal settlement.
"After seeking the assistance of a passing motorist, he was taken to Harare police station unharmed."
Following a search the hijacked car, a Volkswagen Sharan, was found in Lingelethu West. The body of the 28-year-old woman was on the back seat.
Traut would not comment on how she was killed, saying an autopsy would first be conducted. He would also not disclose their names or where in they UK they were from. They arrived in Cape Town last Thursday.
Said Evans: "The tourism safety and support team have been at the scene since 07:20 this morning. We arranged counselling and accommodation for the husband.
"We are obviously devastated by the tragedy. We have had no incidents from the World cup up until now."
Winde said the husband had family in the Eastern Cape. They were coming up to join him. From what he understood the couple had decided, after a tour of the winelands, to drive through Gugulethu to "look at some of the nightlife".
He expressed his condolences to the relatives.
"It's a huge shock to wake up to on a Sunday morning."
The British High Commission in Pretoria has offered to help the victims' families.
"We are aware of the situation... and we're offering consulate assistance," spokesperson Gary Benham told Sapa.
"We cannot give out any information about the couple... it will be up to the family whether to release details or not."
The two attackers were still at large.
Anyone who could help police catch them was asked to contact the investigating officer, Colonel Riaan Theron on 082-463-8706, or Crime Stop on 08600-10111.