Symington, 27, has made 148 starts over five seasons with the club, scoring 36 goals.
He said: "It's good to know you're in the manager's plans and hopefully, we can pick up where we left off and get the promotion which we deserve.
"It was a simple decision, I think it'll be the same for all of the lads just because of the environment we have."
Goalkeeper Atkinson, 26, has been the number one at the club for the last two seasons, making 47 starts and keeping an impressive 21 clean sheets.
He said: "It's good to know what I'm doing next year.
"It was just a case of Danny (Grainger) wanting to keep me or not, and he did after speaking to him.
"It's nice to have it done and dusted so I can get ready for the new season."
Keep up-to-date with our exclusive email newsletters.
Subscribe