Hamer was perhaps best known for saying: "I'm sick and tired of being sick and tired."
Hamer was born to sharecroppers in 1917 and later worked as one and as a timekeeper on a plantation in Sunflower County, near the Mississippi River. She died of cancer in 1977.
She drew national attention in 1964 when she and other members of the racially integrated Freedom Democratic Party challenged the seating of Mississippi's all-white delegation to the Democratic National Convention.
She also helped register black voters when doing so put her own life in danger, and she aided Freedom Summer workers who challenged Mississippi's deeply ingrained system of segregation in 1964.
The statue — made by New Jersey sculptor, Brian Hanlon — was dedicated one day before what would've been Hamer's 95th birthday.
Former Greenville, Miss., Mayor Heather McTeer was at ceremony and said Hamer remains an inspiration for people who have ever been told they can't accomplish what they want to do.
"She, to me, represents the fearlessness of women in politics and women who were standing up for civil rights," McTeer said. "In the face of danger, she still was able to stand unafraid and with a fierce gracefulness, express what was happening."
State Sen. Willie Simmons, D-Cleveland, represents an area where Hamer once unsuccessfully ran for the Senate. He said her legacy remains strong.
"She was a phenomenal woman," Simmons said after Friday's ceremony. "She motivated people."
Charles McLaurin of Indianola, Miss., who knew Hamer through his own civil-rights work, said this past summer that he has long wanted to see a statue of Hamer standing tall in the Mississippi Delta.
"'Stand up and be counted' was one of her themes," McLaurin said. "When children see this statue, they'll know they can stand up and be counted."