Borthwick, who is part of Eddie Jones’ England coaching set-up and helped guide the Red Rose men to an unbeaten 2016, will be joined in the coaching team by Rob Howley and Andy Farrell.
“It is an honour,” said Borthwick of the role. “I think the challenge is an exciting one.
“To come together and make a cohesive pack is exciting.
“The players will bring different strengths, and we need to bring it together quickly in a short space of time. This tour gives us that opportunity to do something fantastic.
“Every one of the players that are going to be involved in this are going to be desperate to prove and play the very best they can.”
The 37-year-old retired from professional rugby two-and-a-half years ago, after earning 57 international caps for Englabnd and making 265 Premiership appearances.
He helped guide Japan through their best ever World Cup campaign in 2015, and took on the England role in December last year.
The former Bath and Saracens lock is known for his attention to detail at the set-piece, and says his transition from player to coach has been an amazing journey so far. “One thing I have certainly learnt about coaching is don’t look back too much, you have to keep looking forward, and that is what I have tried to do,” he said. “I keep trying to learn, and keep trying to be a better coach.”
Gatland was looking forward to getting down to work with Borthwick
“Steve has done a great job in shaping the England pack,” said Gatland.
“He played a major role in their recent run of success, so I’m looking forward to working with him.”
The Lions have a busy schedule spanning June and July next year, where they will play all five Kiwi Super 15 franchises, the Maori All Blacks, a Provincial Union XV as well as three Tests against the All Blacks. The squad will be announced on 19th April.