Ms. Rachel is showing her support for fellow children's entertainer Danny Go ... after his son passed away.

The YouTuber shared a post encouraging members of the "parent and caregiver community" to turn on Danny Go and send thoughts and prayers to him and his family.

She says she's very sorry for their loss ... and she's thinking of their "son's amazing joy and their immense pride."

As we told you ... Danny announced his son Isaac's passing in a social media post on Friday -- writing a personal message to his late son which included, "Your 14 years were full of so many challenges, but you met them all with such grit…and you somehow kept your trademark joy in spite of it all."

He added that being Isaac's dad was "the honor of a lifetime."

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Danny announced in December that Isaac had stage 3 cancer ... and, last month, announced he'd entered hospice care. Danny canceled his tour so he could maximize his time with his son.

Isaac was just 14 years old.

RIP