Brentford boss Thomas Frank is delighted for Ivan Toney after his first England call.
He has 17 goals and seven assists in 41 Premier League appearances and scored a hat-trick in Brentford's 5-2 win over Leeds on 3 September.
"We have been tracking him for a long time," said Southgate. "I had a good chat with Brentford boss Thomas Frank about him last season.
"His form and his qualities - not only his goalscoring but his technical ability, build-up play and aerial prowess - gives us a different threat to some of the other players we could pick."
Toney is the first Brentford player to receive an England call-up since Les Smith in 1939.
Frank said it was a "fantastic day" for everyone at Brentford, adding: "He is one of our leaders and has excelled as a player and a person.
"For the staff, it is a massive moment. To have someone in the England squad is a huge achievement for everyone at the club."
