The presenter, 45, took to Ruth’s social media page to compliment the star’s looks.
Ruth, 60, shared an image of herself in a blue jumper with star patterns across it as she posed with a smile.
The one-time Big Brother contestant wrote to Ruth on the post: “What a beauty [heart emoji]”.
Ruth has yet to like or reply to Alison’s comment on the post.
The social media moment comes after it was revealed by the Daily Mirror that Alison and Dermot O’Leary will replace Ruth and husband Eamonn Holmes for Friday shows of This Morning.
Ruth and Eamonn have been presenters on the beloved ITV morning show for 14 years.
Bosses were said to be impressed by Alison and Dermot’s chemistry together when they have fronted shows previously.
Alison has previously been a fan-favourite for her interviews and segments as a roving reporter.
“They have real warmth,” an insider said. “It’s time for a change and they are perfect.
“Eamonn is pretty furious and everyone feels for him and Ruth, they are well liked on the team, but sometimes tough decisions have to be made.”
Alison was even recently trusted by bosses to guest-edit the show for a day.
“It will just be a joy!” she said at the time. “There will be nothing about lockdown or coronavirus.
“There’ll be a lot of recipes and food… and maybe a little bit of fashion and fun. It’s going to be great and I’m excited to be the boss.”
Despite the decision at This Morning, Ruth is said to be staying on as an anchor for Loose Women where she remains popular with viewers.
The changes, made by show boss Martin Frizell, are expected to roll out in the New Year.
This Morning continues on weekday mornings on ITV from 10am.
Do you have a story to sell? Get in touch with us at email@example.com or call us direct 0207 29 33033.