She will replace Kathryn Holland, who, it emerges, joined FTSE 100 pub-chain owner Mitchells & Butlers (M&B) as its director of corporate affairs earlier this month.
When she arrives at ITN, Evans will report to chief executive Mark Wood, overseeing a team of six.
The company provides news for ITV and Channel Four, plus mobile operators Orange, 3 and O2, and online brands Yahoo! and MSN.
ITN last year secured a contract to produce Channel Four News for a further five years in a deal worth more than £100m. But its contract for ITV News is up for review in 2008. In her WHSmith role, Evans - who declined to comment - is believed to report to the company's HR director, while working closely with chief executive Kate Swann.
PRWeek understands that WHSmith has yet to decide on how to replace Evans. At M&B, Holland effectively replaced former head of comms Kate Peers, who has now taken up a senior marketing manager role. She oversees four people, reporting to CEO Tim Clarke.
Holland, who is working alongside director of public affairs Simon Ward, said: ‘M&B approached me and the leisure sector is one I know well, having previously worked at Intercontinental Hotels, so this move is a natural step.'