Omeruo believes that his three-month stint with Boro helped him secure a place in the Nigeria squad for next month's World Cup in Brazil.
The centre-back already has 14 international caps for his country at the age of 20 and is off to his first World Cup, where the Super Eagles face Argentina, Bosnia & Herzegovina and Iran in the group stage.
"I'm happy that I didn't disappoint [Karanka]," Omeruo, who made 14 appearances for Boro in the second half of the season, told FIFA.com.
"I knew I had to play a lot of games to be fit for the World Cup and also to make the squad.
"I had the chance to do that at Middlesbrough so it's been a really good season for me."
Omeruo is yet to make an appearance for Chelsea since joining the Blues as an 18-year-old two years ago.
Click here for Sports Mole's all-time Nigerian Top 10 as part of our World Cup countdown.