Solomon, 59, died Monday, the 49ers said in a statement. He had been battling cancer.
"The 49ers lost a member of our family today. We'll miss you, Freddie Solomon. Our prayers go out to your family," 49ers president and CEO Jed York said on Twitter.
Solomon was a second-round draft pick by Miami in 1975 and played three seasons for the Dolphins before he was traded to San Francisco, where he made his mark as an important part of Bill Walsh's West Coast offense.
He played his final eight seasons with the 49ers and finished his NFL career with 371 catches for 5,846 yards and 48 touchdowns.
Jerry Rice, considered the best wide receiver in NFL history, said Solomon was influential in teaching him about work ethic and professionalism.
"He inspired me to go out there every day and emulate him," Rice said in a statement released through the 49ers.
Quarterback Joe Montana considered Solomon "a dear friend and a great teammate."
"There was no one who gave more on and off the field than Freddie," said Montana. "The kindness he demonstrated was inspirational to all that knew him, and a joy to be around. The warmth of his smile will be forever embedded in my mind and heart."
After he retired, Solomon spent much of his time volunteering his service to the community. He was named the University of Tampa's Athlete of the Century in 2002.