The deal to bring the 18-year-old midfielder to the Barclays Premier League has been in place for some time, but the Magpies have now formalised the move on a five-year contract.
In Toon: Alan Pardew has signed Lens starlet Abeid on a five-year deal
Reserve team manager Peter Beardsley said: 'We are delighted to bring Mehdi to the club.
'He is a bright, young talent and we think he has an exciting future ahead of him.
'After an impressive trial with us earlier in the year, I'm looking forward to working with Mehdi and developing his talent.'
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