The former Swansea City and Leeds United boss joined on a three-year deal last Friday, and was officially unveiled on Monday.
Monk says that despite the disappointment of relegation last season, the foundations in place at Boro made it an easy decision to come to Teesside.
"I wanted the right challenge and all the boxes were ticked at Boro," he said.
"I had talks with the new people [at Leeds] but we couldn't quite find an agreement.
"Everyone knows the passion and desire Steve Gibson has for this club. Once I spoke to him it was clear this was the right opportunity.
"It's good to be working with that clarity throughout the club. The structure, the ambition, the squad we have here. It is a fantastic club and I'm excited for it."
Having experienced the second tier with Leeds last season, Monk believes it is a division as competitive as it has ever been - but stresses that promotion at the first time of asking remains his focus.
"The objective is getting up at the first attempt. I've signed for three years but I'd like to think we can get up at the first attempt and build from there," he said.
"I have experience of this league and I know how difficult it is. But we know the size of the challenge and we are looking forward to it.
"I'm really excited to be working with the players that are here. They have a lot of talent. I know they've had a big disappointment, but the failure would be a failure to respond, not what happened last season.
"I've worked under pressure throughout my career. That's how I work best. Yes, the club have had a very difficult season but there are very strong foundations - it is my job to give confidence back to the club and the fans."