The Celtic and Liverpool great shared the news in a statement published on Liverpool FC’s website on Tuesday, June 2.
The 74-year-old, who was born in Dalmarnock, noted that his treatment is “going well” and asked for his privacy to be respected at this time.
Sir Kenny said: “As my inadvertent social media post has indicated, I am currently undergoing treatment for cancer.
“Unlike my mobile phone use, the treatment is going well. Ideally, this would have remained private because that’s the way it should be, but my useless technology skills have forced my hand.
“Obviously, I did not mean to make this matter public, so I would appreciate it if the privacy of my family and myself is respected.
“As ever, thank you to the wonderful medical staff who have shown incredible care and discretion, not just for me but for many, many others.
“They are a credit to themselves.”
READ NEXT:
A Liverpool FC spokesperson added: “Sir Kenny Dalglish has confirmed he is undergoing treatment for a cancer diagnosis.
“The support, best wishes, and love of everyone at Liverpool FC are, and will continue to be, with Sir Kenny and his family.
“The club would also like to underscore his request for privacy moving forward.”
Fans flooded social media with messages of support.
READ NEXT:
One person said: “We’re all with you, King Kenny.”
A second added: “My heart is with you, Kenny. Keep fighting.”
Meanwhile, a third commented: “Sorry to hear this, I hope treatment goes well.”
Sir Kenny managed Liverpool to three league titles and two FA Cup triumphs.
During his career, he made 338 appearances for Celtic and 515 for Liverpool.
The forward earned a record 102 caps for the Scotland National Team, scoring 30 goals, and went on to win the Ballon d’Or Silver Award in 1983.
Sir Kenny was then knighted in 2018 and has been inducted into both the Scottish and English Football Halls of Fame.