Source: Team_Talk
Pilgrims snap up Benin defender
The 21-year-old, who was also being chased by Aberdeen, joins the Pilgrims on a three-year contract after playing in Saturday's 2-0 friendly win at Morecambe.
Argyle boss Paul Sturrock said: "He's tall, athletic and has got a decent left foot.
"He's a good passer of the ball and I believe he has the potential to be a very good player for us."
Johnson could feature in Wednesday night's friendly against Hearts at Home Park.