Mix sugar and huckleberries together in a stockpot; bring to a boil, stirring constantly. Stir pectin into berry mixture and boil, stirring constantly, for 1 minute. Remove pot from heat and skim foam off the top using a metal spoon.
Sterilize the jars and lids in boiling water for at least 5 minutes. Pack jam into hot, sterilized jars, filling to within 1/4 inch of the top. Run a knife or thin spatula around the insides of the jars after they have been filled to remove any air bubbles. Wipe the rims of the jars with a moist paper towel to remove any food residue. Top with lids and screw on rings.
Place a rack in the bottom of a large stockpot and fill halfway with water. Bring to a boil and lower jars into the boiling water using a holder. Leave a 2-inch space between the jars. Pour in more boiling water if necessary to bring the water level to at least 1 inch above the tops of the jars. Bring the water to a rolling boil, cover the pot, and process for 5 minutes.
Remove the jars from the stockpot and place onto a cloth-covered or wood surface, several inches apart, until cool. Once cool, press the top of each lid with a finger, ensuring that the seal is tight (lid does not move up or down at all). Let stand at room temperature for 24 hours. Store in a cool, dark area.