The free-agent deals were announced on Friday.
Garon agreed to a two-year, $2.6 million deal and will be the backup to Dwayne Roloson, who is returning to the Lightning on a one-year, $3 million contract signed Thursday. Garon was 10-14-6 record last season with Columbus.
Ouellet got a one-year, two-way contract. He spent the past two seasons playing in Europe.
The Lightning signed right wing Brett Connolly, their 2010 first-round draft pick, to a three-year, entry-level contract.
Also, Lightning center Steven Stamkos, who has combined for 96 goals the past two seasons, became a restricted free agent. Contract talks are ongoing with Tampa Bay.