A mourner at a memorial for the West Side Highway terror attack on Wednesday refused to shake Mayor Bill de Blasio’s hand — after the city only let loved ones know about the event at the last minute.

Hugh Hales-Tooke stared straight ahead and refused to acknowledge de Blasio’s presence as Hizzoner stuck out his hand while greeting those gathered to grieve the eight people mowed down by a truck-driving terrorist on the pathway a year ago.

Hales-Tooke said his friend Monica Missio, whose son Nicholas Cleves died in the massacre, missed the event because she was only told about it late Tuesday afternoon and was out of town.

“She’s very hurt. She was very hurt,” he told The Post.

Adding insult to injury, de Blasio then forgot to read out any of the victims’ names during his address at the service — despite managing to name-check all of the politicians who showed up.

When family members objected after the memorial, the mayor returned to the podium to apologize for the faux pas.