The post covers media and PR, brand, internal comms, investor relations, regulatory and public affairs. Reynolds has also joined the company's Executive Committee.
The new position is intended to strengthen Biffa’s corporate affairs function, bringing together regulatory engagement and both the internal and external comms teams. These teams were previously located in the operational and HR areas of the business.
Biffa said in a statement: "Cory has a strong track record in communications and public affairs across utilities and the public sector.
"She will play a vital role in continuing to develop Biffa’s communication with our customers, colleagues, investors, partners and regulators, as well as embedding Biffa’s reputation as the leader in UK sustainable waste management."
Biffa, which entered the FTSE 250 in March this year, generated revenue of £1.1bn in 2020. It employs more than 8,000 people in the UK.
Reynolds worked at Southern Water for more than five years, latterly as director of communications, brand and public affairs, before she left earlier this year. The former BBC journalist was previously head of comms at Brighton & Hove City Council.
A Southern Water spokesman said: “The recruitment process for Cory Reynolds’ replacement is underway. Kate Tonge joins as interim head of communications imminently.”