Police have not said if the man who has been arrested is the person in the hoodie.
Detectives hold grave fears that Ms Meagher, a 29-year-old who moved from Ireland to the city three years ago, was abducted while walking home alone last Saturday from a Sydney Road bar in Brunswick.
A police caravan had been set up near the corner of Sydney Road and Hope Street, close to where Ms Meagher was last seen on CCTV footage speaking with the unknown man in the blue hoodie outside a bridal dress store.
Five others were captured on the footage walking past, but one of them has since come forward to be interviewed by police about the hoodied man.
"I told the police he was just a nondescript-looking guy," Brunswick resident Dan Gregson told Fairfax.
"There was nothing strange about him or I would have noticed."
Ms Meagher had left Bar Etiquette on Sydney Road at 1.33am (AEST) after drinking with ABC colleagues.
But police say she never completed the five-minute walk to the flat she shares with her husband, Thomas, who is not being treated as a suspect.
In the CCTV footage, the man in the hoodie walks back and forth, speaks briefly to Ms Meagher, and then walks off ahead of her.
She then speaks to her brother on her mobile for two minutes, walks out of view of the camera and has not been seen since.
Police would not confirm on Thursday a News Limited report that additional CCTV footage shows the same unknown man running towards Ms Meagher, or a witness report that a car had performed a U-turn towards her.
- AAP
