With Virat Kohli following Rohit into test retirement, Gill will lead a depleted India team in a five-test tour of England starting on June 20th.
Jasprit Bumrah, 31, has been Rohit's deputy and captained India in two tests in Australia last season but chief selector Ajit Agarkar said they could not risk burdening the pace ace with leadership.
"I think he's more important to us as a player. We want him fit," Agarkar told a press conference in Mumbai.
"There's always that extra burden when you are leading and managing 15-16 people, it takes a lot out of you.
"We'd rather have him bowling as well as he does than putting that extra burden on him. He's aware of it.
"We had a chat with him and he's okay with it."
India will begin a new World Test Championship cycle under the 25-year-old Gill, who has impressed as captain of the Gujarat Titans in the ongoing Indian Premier League.
Agarkar said he hoped the captaincy would inspire Gill, an all-format international, to grow even better.
"You can look at it as a burden or you can look at it positively," former India pacer Agarkar said.
"In franchise cricket, he's obviously relishing the role. It's obviously going to be a lot harder but those are the challenges you face playing international cricket.
"He's been around for two to three years in all formats. He can fall back on that experience."
"I'm sure he's relishing the opportunity. I mean, who would not want to captain India in test cricket?"
Bumrah was unlikely to play all five tests in England, Agarkar said, while fellow seamer Mohammed Shami had been left out following a late injury setback.
Sai Sudharsan will hope to make his test debut in England, while fellow batsman Karun Nair is in line to play his first test since 2017.
Wicketkeeper Rishabh Pant has been named Gill's deputy in the test squad.
India squad
Shubman Gill (captain), Rishabh Pant (vice captain), Yashasvi Jaiswal, KL Rahul, Sai Sudharsan, Abhimanyu Easwaran, Karun Nair, Nitish Kumar Reddy, Ravindra Jadeja, Druv Jurel, Washington Sundar, Shardul Thakur, Jasprit Bumrah, Mohammed Siraj, Prasidh Krishna, Akash Deep, Arshdeep Singh, Kuldeep Yadav