Defender Ramage and midfielder Garvan will be playing Premier League football next season after agreeing new two-year deals.
Former Newcastle and QPR centre-half Ramage, 29, made 43 appearances last season and was an unused substitute in Monday's play-off final win over Watford.
Ex-Ipswich playmaker Garvan, 25, played 84 minutes at Wembley in what was his 32nd appearance of the season.
Both players have now committed their futures to the Eagles until the summer of 2015.
Palace have also confirmed Jazz Richards and Alex Nimely have returned to Swansea and Manchester City respectively at the end of their loan deals.
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