In their first year, individuals of Asterina phylactica are all males but in the following year they become hermaphrodite and produce both sperm and eggs. The breeding season is late spring and several individuals come together in a group. Sperm is liberated into the sea and the eggs are fertilized. The developing embryos are retained under the starfish where they are brooded for about three weeks. The eggs have direct development and metamorphose into juvenile starfish which crawl out from under their mother and disperse.

The typical habitat for this species is rock pools on exposed coasts with much encrusting coralline algae. It is a tolerant species and able to adapt to a range of different salinities and temperatures.