The 23-year-old has arrived for an undisclosed fee, having previously played under Cardiff boss Ole Gunnar Solskjaer in the duo's home country.
Berget is Solskjaer's third signing for Cardiff, following Mats Moller Daehli and Magnus Wolff Eikrem, with all three having played for the manager as Molde won back-to-back Norwegian titles in 2011 and 2012.
Solskjaer expects Berget to add a new dimension to Cardiff's frontline and feels the player will have no problems adapting to the English game.
"I’m delighted to welcome Jo to the club. He went through his medical last night and signed his contract this morning, " Solskjaer told the club's official website on Friday.
“He’s a forward and full Norwegian international and arrives on a very good deal for us.
"He knows the way I want to play; he's a secondary frontman and is a very strong and intelligent footballer. He'll do well for us."
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