Karanka believes Essien, who joined on a season-long loan from Chelsea, will be a great addition to the squad.
Essien will reunite with head coach Jose Mourinho, who managed the powerful midfielder at Stamford Bridge.
The move was triggered by confirmation of Lassana Diarra’s impending departure to Russian Premier League club Anzhi Makhachkala.
“Everything was left for the last minute, there were calls during the training session yesterday,” Karanka said.
“Lass (Lassana) Diarra received an offer he couldn’t refuse.
“So the club worked to find an alternative, and this was Michael Essien, a player our manager knows and trusts.
“They know each other from Chelsea. He’s strong, but the most important thing is … professionalism.
“He’s a great person as well, and he comes here to add up in a quality squad. No doubt it’ll be a great signing and an important player for us.”
With the international break looming, Karanka feels Real’s match at home to Granada on Sunday is a must win, as they look to build momentum following a slow start to their title defence.
“The team faces the next game, fresh from winning its first title of the season,” he said, referring to Real’s Spanish Super Cup triumph over two legs against Barcelona.
“And after having struggled in La Liga, so far we are hoping to win before the international friendlies break.
“We’d like to repeat our performance of last sunday in front of our fans and start a winning streak in La Liga that allows us to keep fighting on the top of the table.”