After Southampton's Virgil van Dijk headed wide and Fraser Forster produced a fantastic reaction save to deny Jermain Defoe, AFC Bournemouth took a first-half lead.
Ryan Fraser slotted in from Andrew Surman's pass after Saints defender Wesley Hoedt had been caught in possession.
But Austin, who made his name at the Cherries' non-league neighbours Poole Town, scored from Nathan Redmond's cutback on 61 minutes.
Austin headed narrowly over as Saints pushed for a second but the point leaves them 11th, two points and three places above their opponents.
AFC Bournemouth: 9 Dec v Palace (A)
Southampton: 10 Dec v Arsenal (H)