Johnson, 23, who in the past played for Dundee United, was on loan at Akritas Chlorakas last season.
He may make his Accies debut at the Ross County home on Saturday after receiving foreign approval.
“I’m back in Scotland now and I’m more determined and more mature on and off the field,” Johnson told Hamilton’s website.
The winger has scored six goals in senior appearances and scored one for Dundee United in 2016.
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