Santo, who died at age 70 in 2010, spent 14 years with the Cubs as their third baseman (1960-73), earning nine trips to the All-Star Game while hitting 342 home runs with 1,331 runs batted in.
Later becoming a beloved radio announcer for the team, he was the subject of a long campaign by fans and his former fellow players to gain him entry into the Hall.
"I don't know of anyone who had more friends than Ron Santo," his wife Vickie Santo said. "This is not a sad day. This is a great day. Celebrate with Ron and for Ron. I am certain Ronnie is celebrating with us right now."
Larkin, meanwhile, earned 86.4 percent of the vote to make the Hall in his third year of eligibility. Spending all 19 years of his career with Cincinnati, Larkin hit .295 with 198 home runs, 960 RBI, 2,340 hits and 379 stolen bases over his career.
"I got a chance to play on great teams with great people," he said.