Though no financial details were disclosed, media reports said Albion had paid 13 million pounds for Chadli.
"I feel very good to be here. It came very quickly but I spoke to the club and they have a good team, a good manager," Chadli told the club's website.
The Belgian international, who joined Spurs from Dutch side Twente Enschede in 2013, made 119 appearances in all competitions for the London club.
Albion, who have picked up four points from their first three league games, visit Bournemouth for their next fixture on Sept. 10.
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(Reporting by Nivedita Shankar in Bengaluru; Editing by Tony Jimenez)
