A 32-year-old man has been arrested on suspicion of the murder of Joanna Yeates, Avon and Somerset Police said.
The 25-year-old's body was found on Longwood Lane, Failand, North Somerset, on Christmas Day morning, sparking a huge police operation.
A police investigation was launched when Miss Yeates's boyfriend Greg Reardon, 27, reported her missing after he returned to Bristol on December 19 following a weekend away visiting family in Sheffield.
Miss Yeates was not seen again until her body was found on December 25.
Police have said there was no evidence she had been sexually assaulted but they have not ruled out a sexual motive.
The latest breakthrough came a day after police revealed that more than 300 people had contacted detectives investigating the murder in the 24 hours after a reconstruction of Miss Yeates's final movements was filmed.
The landscape architect's last journey, which started after she left work on December 17, was retrodden by an actress on Tuesday night and filmed for the BBC's Crimewatch. The reconstruction focused on what she did after she left her firm, BDP, in Bristol city centre.
Seen on CCTV in a Waitrose supermarket at the Clifton Triangle, she then went to a Tesco Express in Clifton village where she bought a pizza.
Detectives said Miss Yeates had made it home to her flat because her shoes, coat, mobile phone, purse and keys were found there - although the pizza, the wrapping and its box are still missing along with Miss Yeates's ski sock. On Tuesday night police revealed that tests showed she had not eaten the pizza before she died.
Detective Chief Inspector Phil Jones, Avon and Somerset Police's senior investigating officer, said: "I would like to thank the public for their continued support for the investigation and the information they have provided to us."