A popular business or businessperson to whom job candidates naturally gravitate. Magnet employers often have brand name recognition behind them, and they typically offer higher pay or better benefits than their competitors, thus making them a "magnet" for job seekers looking for superior compensation.
Unfortunately, magnet employers are not terribly common. Some companies offer lower pay and higher benefits, while others are more generous. But magnet employers often attract the best and brightest employees, which can make the company more profitable in the long run.