Donny Osmond is mourning the loss of his older brother, Alan Osmond, who died at the age of 76. The heartfelt tribute shared on April 21 quickly touched fans who have followed the Osmond family for decades.

In an emotional Instagram post, Donny reflected on an old childhood photo showing Alan with his arm around him.

"This is one of the earliest pictures I have of my brother Alan and me. Even back then, you can see that he had his arm around me, watching over me," he wrote, according to People.

Donny added, "That's who he was. My protector. My guide. The one who quietly carried so much responsibility so the rest of us could shine."

Alan Osmond passed away on Monday, April 20, according to a family spokesperson who confirmed the news to ABC4 in Salt Lake City. His wife, Suzanne, and their eight sons were by his side when he died.

The cause of death has not been made public. Alan had previously stepped away from performing after being diagnosed with multiple sclerosis, but he remained active in charity and family work.

Alan Osmond Remembered as Family Leader

Donny described his brother as the foundation of their family's success. "Alan was our leader in every sense of the word. His tireless work helped build everything we became," he wrote.

"I will always be grateful for the sacrifices he made and the love he showed — not just to me, but to every member of our family."

Alan was the oldest of the Osmond siblings and played a key role in shaping the family's music career. He performed alongside his brothers in The Osmonds and worked behind the scenes as a producer on shows like "The Osmond Family Show" and "Donny & Marie."

He also helped create the Children's Miracle Network Telethon, which has raised billions for children's hospitals, and founded the One Heart Foundation to support orphans, US Magazine reported.

Family members also shared their grief online. Marie Osmond described Alan as a protective and steady presence in her life, while other relatives praised his leadership and kindness.

"Gonna miss uncle Alan. No matter the situation, he always had a strong and shining smile," Chris Osmond wrote.

Donny ended his tribute with simple words of love and goodbye: "I love you, Alan. Thank you for always being there for me. Till we meet again."