"It was impossible to be disappointed," said Boro's Head Coach. "Our intensity and approach was excellent. The players played the way I liked and I'd like to say thanks to them for that."
Bolton looked to have set up to avoid defeat and Boro ripped in to them from the start. Diego Fabbrini scored a spectacular opener after seven minutes, then set up Kike to add a second on 17 and a third on 31.
"It was a surprise for me because Bolton changed their shape and the players (before the game)," admitted Karanka. "When you score a goal like Diego did early they then have to change everything. So we had to keep going in the same way and then when we play in that tempo it's difficult to stop us.
"I told the players at half time that I wanted more. I knew it was going to be difficult because it was our first game at home and only the second of the season so we're not 100% fit so I knew it was going to be difficult, but I had to tell them that we needed more because if I had said at half time that everything was done we would've been making a very big mistake.
"Now Kike is scoring, Stuani scored in the last game against Oldham, David Nugent had a chance to score but it's not about who scored - it's about the time. Diego Fabbrini played amazing, do did Clayton, Leadbitter - I can't just say one player."
There was an amusing moment in the first half when Albert Adomah lay down in the technical area after the referee refused to allow him to return quickly after he left the field to replace a boot.
Boro fans were frustrated with referee James Adcock, but Boro's Head Coach was at pains to point out the official was well within his rights.
"When there is a change to a player's equipment then he has to leave the pitch to make that change. He can only come on at the referee's discretion, or when there is a break in play. So while it was funny, it was funny because we won the game. But by the rules the referee was right.
"But I am very happy with everything else today. We have a much better squad than we had last season; I have a very good squad to choose from.
"It's really difficult to pick the best 11, but I'm really pleased as I prefer to go into my office and have to pick 11 players from 23 very good players.
"Today it wasn't just those who started, it was those who came on as well, like Adam Forshaw, Stuani and David Nugent. All of them were brilliant and all of the players on the bench were supporting us.
"The game will be different at Derby on Tuesday, but we will take good things from this game."