Family and friends of the 28-year-old filled Chapel Street in the town centre on Saturday (January 20) standing outside the Tui branch at which she been assistant manager.
Hayes passed away a week earlier after being attacked in the store.
Andrew Burke, 30, of Vincent Street, St Helens, has been charged with her murder and has been remanded in custody until February 19, when he is expected to enter a plea.
A minute’s silence began at 1.27pm, marking exactly seven days since the incident and following the tribute, the crowd broke into a round of applause, The Liverpool Echo reports.
The vigil was organised by staff from businesses in Chapel Street and many shop workers left their stores to join the crowd to pay their respects.
One staff member from a nearby butchers, where Cassie was reportedly a regular customer, told the newspaper: "She was a customer for us, she was really quiet and really pleasant - she would always come in and was always smiling - she is just such a loss.
Her colleague added: "This is an amazing tribute."
A GoFundMe campaign, created in memory of Hayes by Travel Gossip’s Bruce Martin, has so far reached more than £7,000 with the help of the UK travel trade.
The money will go to Hayes’s family to use as they see fit.