The Argentinian shrugged off his recent struggles in front of goal with two close-range finishes before setting up Karim Benzema for a simple late effort in a 5-2 win.
Karanka said: "The other day (against Celta) Vigo he (Higuain) was off target in front of goal and (yesterday) he has scored.
"We know what Pipa is like. We don't need to worry about the chances that are missed, the important thing is to create them in the first place.
"He has scored and that is important for him. The best thing is that he gets the confidence in front of goal that strikers need."
Higuain himself added on www.realmadrid.com: "I am very happy because I scored, made an assist and Madrid won.
"Mallorca came here playing well. They went ahead twice, but the team showed the fighting spirit and style it has. In La Liga we are going to try and keep fighting to the very end."
Emilio Nsue gave the visitors an early lead, but Higuain levelled before Alejandro Alfaro put Gregorio Manzano's side in front again before half-time with a second goal from a set-piece.
A tactical reshuffle at the break gave Los Blancos the lift they needed and goals by Cristiano Ronaldo, Luka Modric, Higuain and Benzema in the second half gave a dominant Madrid the three points.
Karanka said of his team's ongoing set-piece failings: "They are moves that we have been conceding from since the start of the season, errors from set-plays because of lapses in concentration. We are trying to improve.
"In the first half we made lots of mistakes, not just the goals but also in our passing and a lack of concentration on the whole. We spoke during the break and changed the team's tactics."