Martinez announced on Aug. 7 he would officially resign from his U.S. Senate post once Crist chose a replacement to represent the state in the Senate.
Crist said Friday his selection of LeMieux, his former chief of staff, would be a welcome addition to the U.S. Senate, the South Florida Sun-Sentinel said.
"George LeMieux is a tremendous example of that kind of leadership and a great man," Crist said. "His public record and his public service are extraordinary. I am happy for my friend and I am extremely happy for my state."
The Sun-Sentinel said Crist's decision regarding his state's U.S. Senate seat drew immediate criticism from Karen Thurman, head of the Florida Democratic Party.
"In appointing LeMieux, someone who has made millions over the past several years selling access to Crist to the highest bidders among Tallahassee's special interests, Charlie Crist once again put his own political ambition above doing what is right for Florida," Thurman said in a release Friday.