Logan joined ET's Katie Krause on Wednesday and he addressed the revelation, which he said he'd not known about prior to Bieber's announcement.
"I commented on his Instagram. I said, 'Adapt and overcome.' Like, nothing can stop the king," the 24-year-old Internet star and boxer shared. "It's true. He's just been through so much s**t. Bieber knows how to adapt and overcome."
"He said he had been struggling with it and hopefully he's doing much better than he was," Logan added. "My aunt had Lyme disease. That is not a joke of an illness. It's definitely something that will take an effect on your mental [health], physical [health], everything."
"If there's anyone that can beat it, it's Bieber," Logan added.
On Wednesday, Logan's younger brother fellow YouTube superstar Jake Paul had big boxing announcement of his own, when he held a press conference revealing his upcoming fight with YouTube star AnEsonGib. The battle is set as the co-main event of a huge night of boxing from Miami on Jan. 30.
Jake also spoke with ET after the press conference, held at Beauty & Essex in Los Angeles, and echoed his brother's supportive sentiments regarding the singer's Lyme disease diagnosis.
"I haven't spoken to him about that. I haven't seen the reports. But man that's a lot to deal with. I'm sorry to hear that," Jake shared. "I know like how hard and difficult that can be and how serious it can be. So, that's heartbreaking news."
Addressing Bieber through the lenses of the ET cameras directly, Jake shared, "Sorry, Justin. I'm supporting you!"
"While a lot of people kept saying justin Bieber looks like sh*t, on meth etc. they failed to realize I've been recently diagnosed with Lyme disease, not only that but had a serious case of chronic mono which affected my, skin, brain function, energy, and overall health," Bieber began, before confirming that people will find out more in his series. "These things will be explained further in a docu series I'm putting on YouTube shortly…you can learn all that I've been battling and OVERCOMING!!"
"It's been a rough couple years but getting the right treatment that will help treat this so far incurable disease and I will be back and better than ever NO CAP," he concluded.