The 31-year-old failed a drugs test following their 36-8 defeat by Wakefield Trinity on 14 July.
The Super League club said they had received notification from UK Anti-Doping and the Rugby Football League.
A Widnes statement said: "The club fully respects this suspension and are currently reviewing this matter."
Chase won the Man of Steel award in 2011 - a year in which he would later go on to represent England and earn eight caps.
He joined Widnes from the Tigers in May, initially on loan, before the deal was made permanent in July.
BBC Sport's rugby league correspondent Dave Woods
Rangi Chase has been the ultimate enigma since he arrived at Castleford eight years ago. Unbelievably skilful, he has produced some of Super League's most breathtaking moments.
But equally breathtaking has been his often off-field stupidity. His has been a career full of official warnings, last chances and shown doors by a collection of clubs that have lost patience with his extra-curricular activities.
He's come and gone at Cas, Salford, Leigh, Cas again and now, presumably, Widnes. If this latest drug test failure is upheld, there will finally be no way back in rugby league for his mercurial, magical but misguided talents.
Precedent has been set. Gareth Hock, then at Wigan, was banned for two years when he was found guilty of cocaine misuse ahead of a game.  If the same holds for Chase, that would take him to 33. Age alone would probably be against him. But reputation will hold even greater sway.
A premature end to his career, if that's what this is, will surprise no-one but it will sadden many that such skills, such sublime ability that he possesses couldn't have been harnessed for the even greater pleasure of all those who have marvelled at the very best of Rangi down the years.
Widnes Vikings half-back Rangi Chase has been suspended from all training and playing activity after testing positive for cocaine.