The 28-year-old teacher was found dead in Kidbrooke in southeast London earlier this month.
British police said on Sunday that they have arrested a 36-year-old man on suspicion of murdering Sabina Nessa in London.
The 28-year-old primary school teacher was found dead in Kidbrooke, southeast London on September 17.
Detectives believe she was attacked and killed during a five-minute walk to meet a friend at a nearby pub.
The Metropolitan Police force stated a 36-year-old man was arrested overnight in East Sussex and was taken into custody.
"Sabina’s family have been informed of this significant development and they continue to be supported by specialist officers," said Detective Chief Inspector Neil John, from the Met’s Specialist Crime Command.
Two other men have previously been detained and then released under investigation, but police stressed the latest arrest was a "significant development".
In a fresh appeal, police had earlier released CCTV footage of a man who was seen along Nessa's route on the night she was killed.
Her death has fueled fresh concerns that women are not safe on the streets of Britain's capital city.
The killing came just six months after the abduction, rape, and murder of 33-year-old Sarah Everard in south London by a serving police officer. The case shocked the country and saw thousands take to the streets to denounce violence against women.
Hundreds of people held a candlelight vigil for Nessa on Friday, demanding an end to violence against women.
"This feels like we are stuck in a bad dream and can't get out of it," Nessa's sister, Jebina Yasmin Islam, told the crowd.
"Our world is shattered, we are simply lost for words... No family should go through what we are going through."