"Aaron is an important addition for the Islanders," said pro scouting director Ken Morrow. "He is a talented, dedicated player and, at 24 years old, he's just coming into his own as a defenceman.
"His acquisition gives us some depth on the blue-line at the NHL level. Our scouts and our coaching staff are very enthusiastic about Aaron."
If he doesn't crack the big-league lineup in the autumn, he'll get a lot of playing time on the AHL farm in Connecticut.
"He could eat up a lot of minutes and run our power play in Bridgeport," said Morrow. "And he's also a young player you'll see in an Islanders uniform."
In 61 games with Columbus last season, Johnson scored three goals and assisted on 10. In 2005-06, the six-foot-one, 195-pound Nova Scotian was 2-6-8 in 26 games with the Blue Jackets.
He was originally selected by Columbus in the third round of the 2001 entry draft. In 2002-03, his final season in the QMJHL, he was 10-51-61 in 57 games with Rimouski and Quebec.
In three seasons with the AHL's Syracuse Crunch, Johnson played 175 games and was 17-56-73 with 345 penalty minutes.