Paatelainen told the club's official website: "I am delighted to have secured the services of Jonatan, and I am confident that Hibernian supporters will quickly appreciate that we have obtained an experienced international striker who has scored goals wherever he has played.
"He also has experience of the Scottish Premier League, so I'm sure he will settle very quickly into our squad."
Johansson added: "I am delighted to have secured this move to Hibernian and to be coming back to Scotland. I'm looking forward to the new challenge and to be working with Mixu again.
"I recently visited the training centre and was blown away - it really is a fantastic facility. I look forward to training there to get up to speed on my match fitness for the New Year."