The forward, who has duel nationality having been born in Liverpool to German parents, signed the deal on Wednesday.
Glatzel was made captain of the U18s this season and has bounced back following two years on the sidelines through injury with an exceptional run of form.
On signing his first pro-deal with the club, Glatzel told Liverpoolfc.com: “I’ve been at the club for a long time and to sign a professional contract means a lot to me, and on my birthday as well made everything special.
“It couldn’t have come at a better time and I’m excited.