The Loose Women pundit, 55, called on her social media followers to keep their eyes peeled for teenager Owen Harding.
It is believed Owen - a friend of her daughter Maddie - was last seen in Brighton village Saltdean on Thursday evening.
Owen, 16, is reported to have not been in contact with family or friends since then.
Nadia put the call out to her 164,000 Twitter followers and 242,000 Instagram followers yesterday.
Her posts were also shared across social media by her ITV co-stars Stacey Solomon and Ruth Langsford.
This is very out of character for him.
She has also broadcast several similar appeals from her Instagram Stories account.
Nadia noted the teen had been away from home for over 24 hours following a disagreement.
Concerns he may have tried to travel to York
She wrote: "He is 6ft tall with dark hair, he was wearing a black (dark) hoodie and grey tracksuit bottoms with white trainers.
"Owen's mum has told us that this is very out of character for him. He apparently does not have any charge on his phone.
"There were concerns that he may have tried to travel to see his girlfriend in York but he has not arrived there or made any contact.
"Please could you keep a look out especially on The Telscombe Tye, on the Downs and beach areas in and around Saltdean and its neighbouring villages and towns."
Nadia concluded: "Thank you for your support, we would really appreciate you sharing out this post as much as possible."
According to local reports, Sussex Police have said officers searched the beaches last night in a bid to find Owen.
We're all desperately worried
Owen's mother Stella is reported to have told The Argus: "Clearly, it is a really difficult time for everyone at the moment and we're all desperately worried, especially since this is so out of character and our ability to get out the house and find him is limited.
"We think there is a possibility that something has happened to Owen and are appealing for those in Saltdean, Telscombe, Ovingdean and Brighton, to look out for him.
A Sussex Police spokesman asked people to get in touch if they have any information.
"Anyone who sees him or knows where he could be is asked to report it online or call 101, quoting serial 1198 of 26/03," they said.
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