The 45-year-old presenter was hosting alongside Dermot O'Leary as the pair have replaced Eamonn Holmes and Ruth Langsford.
They were chatting to Graham Norton about his Virgin Radio show when Alison made the cringeworthy 'dead dog' gaffe.
She said to Graham: "The last time I saw you, you were with your dog out and about! I've just been told I'm going to get a four-legged friend.
"Have you still got your dog?"
Graham replied: "No. dead."
Dermot O'Leary fell into fits of laughter as Graham chuckled too.
Alison remarked: "I'm gutted. I'm so sorry I'm absolutely devastated."
Luckily, Graham found the situation funny as he laughed: "Sorry I'm being horrible."
Despite the mortifying gaffe, viewers adored watching Alison and Dermot as they made their This Morning debut.
This Morning fans rave over Alison Hammond and Dermot O'Leary after presenting debut.
A third added: "I b****y love Alison and Dermot."
"I am actually so happy that it's Alison and Dermot now", gushed another.
Some fans did miss Eamonn and Ruth though, as one wrote: "Missing Eamonn and Ruth already."
Another remarked: "Gonna miss Eamonn and Ruth on a Friday, but I do like Alison and Dermot too but just feels weird."
Ruth and Eamonn had their last Friday episode last year, before they are replaced by Alison and Dermot.
Hammond paid tribute to the legendary duo, who had been fighting back tears during their last episode.
She tagged the both of them on Twitter, writing: "A class above the rest," and a heart emoji.
This Morning airs weekdays at 10am on ITV.