A knife-wielding mugger slashed a woman on the neck last night after robbing her of her cell phone and iPod in Hell’s Kitchen, authorities said.

“She was shaken up like she couldn’t believe it,” said a doorman at 511 W. 46th St., where the 41-year-old woman sought help.

“She had a deep slice on the left side” of her neck, he added.

She was taken to St. Luke’s Hospital for treatment.