On August 5, 2019, local news source Dispatch reported that he and TWICE's Jihyo were dating. Later that day, the reports were confirmed by both agencies. Also, it was revealed the two were introduced to each other through 2AM's Seulong.
On November 9, 2020, JYP Entertainment confirmed that the couple had broken up due to busy schedules.
On December 4, 2019, KONNECT Entertainment released a statement stating that Daniel visited the hospital due to poor health caused by a weak immune system and psychological anxiety starting from the first half of the year. He was then diagnosed with depression and panic disorder after a detailed examination and treats it through psychotherapy and medication. As he had been expressing more severe symptoms of anxiety, he will be taking a temporary break from activities to focus on his recovery.
Him and fellow member and label mate Jisung were once back-up dancers for Cao Lu and Sihyun during their trainee years.
He has a maternal aunt who lives in Canada where he learned to speak English.
He had been B-boying since junior high school and was the first B-boy in the rookie battle in the Busan scene.
He changed his name to Kang Daniel because he was worried that it will be hard to pronounce his birth name Eui Geon.
He has four cats named Rooney, Peter, Ori and Zhang-ah.
Daniel initially thought that the former two were male but actually female.
It was revealed that his fan cafe donated ₩1.1 Million Won (Approximately $980) to Korea Animal Rights Advocates (KARA), an animal protection organization, in wishes to get him to the Top 11 and because he loves animals.
It was revealed that him, fellow member Woojin, and BTS's Jimin were in a dance competition called Busan City Kids.
He has trained for 2 years and 1 month, if including Produce 101 Season 2, it would be 2 years and 5 months.
He sometimes has the habit to grind his teeth while asleep.