Lock Beukeboom, 26, has agreed a two-year deal, while wing Evans has signed a one-year extension along with Matt Bolwell, John Stevens and Bar Bartlett.
Speaking about Bolwell and Stevens, coach Alan Paver said: "They are two young guys who have proved their worth.
"This season Bar has been another huge contributor and we are over the moon to sign such a quality player."
Pirates, who are sixth in the Championship, play their final game of the season against Bedford on Saturday and now have 24 players signed on for the 2017-18 campaign.
Canada internationals Brett Beukeboom and Matt Evans are among five Cornish Pirates players to sign new contracts.