Bam Margera finally got the green light to see his son -- this after recently crossing a huge milestone in sobriety -- and he has plans to see the boy for Christmas ... TMZ has learned.
David Glass -- the attorney repping Bam's estranged wife, Nikki -- tells us the former "Jackass" star has, indeed, been granted monitored visitation with their young son, Phoenix. We're told Bam can see Phoenix with a professional supervisor if/when he's in Southern California ... which is where Nikki lives with the kid.