The incident happened in October 2018 as the 35-year-old woman was walking with the boy in Queens after picking him up from his pre-school.
Authorities said 58-year-old Derrick Chirse punched the woman multiple times, knocking her unconscious before stealing her purse. The boy was unharmed.
Chirse was indicted by a grand jury on charges of robbery, assault, criminal possession of a weapon and endangering the welfare of a child.
Good Samaritans chased him into a nearby backyard but he jumped over three fences before he managed to climb onto the roof of a nearby CVS and escape.
"After beating and robbing the defenseless woman - whose toddler son witnessed the vicious assault - the defendant fled the location," said Queens Chief Assistant District Attorney John Ryan.
Chirse was arrested the following day at a homeless shelter in Brookyn after the release of surveillance video of the assault.
He faces up to life in prison if convicted.
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