Police Public Relations Officer, DSP Ahmad Muhammad, told the News Agency of Nigeria in Port Harcourt, the Rivers State capital, that Kogbara was freed in the early hours of Saturday.
Muhammad said the state Commissioner of Police, Musa Kimo, had already visited Kogbara in her family residence in Port Harcourt.
Muhammad said Kogbara was in good condition and had reunited with her family.
The police spokesman, however, did not say if any ransom was paid before she was released or if any arrest was made.
Kogbara was kidnapped in front of her house in the Nkpogu area of Port Harcourt in a Honda SUV.
She worked for the BBC, Channel 4, the Sunday Times and the Mail and has been reporting for the Vanguard newspaper for some 30 years.
She was visiting her family in Rivers State when she was abducted.
Speaking about Kogbara, Kimo said: “Let me assure you and her family that we are doing all that is humanly possible to safely rescue and reunite her with you and her family members.”
The Nigerian Guild of Editors (NGE), International Press Centre (IPC), Committee to Protect Journalists (CPJ) and Nigeria Union of Petroleum and Natural Gas Workers (NUPENG), among others, had campaigned for her release.