A Bronx mom allegedly let her 7-year-old daughter drown in a hotel pool — while leaving her 5-month-old baby in the room alone — as she downed drinks at the bar, prosecutors announced Tuesday.

Erica Baez, 41, is now being held without bail on second-degree manslaughter and endangering the welfare of a child charges in the Jan. 13, 2022 horror at a Marriott Hotel in Melville.

The tragic girl, Katlyn, died May 1 after spending more than a year on life support, Suffolk County prosecutors said.

Baez had been staying at the hotel with her boyfriend, her 5-month-old son and Katlyn when the boyfriend left for work early that day, the Suffolk County District Attorney’s Office said.

The mom had asked hotel staff to open the indoor pool around 3:30 p.m. — with workers warning her that no lifeguard was on duty and that she’d have to stay with her child, the DA’s office said.

But Baez instead headed to the hotel bar where she ate and drank an alcoholic cocktail while her daughter played alone in the pool for 30 minutes, prosecutors claimed.

The mother went to check on the child but then left her alone again while she went up to the hotel room to see her infant, who was also alone, the DA’s office claimed.

Baez went for a second cocktail and left the daughter for over 30 minutes before returning to the pool to find the girl “floating lifeless in the pool” the office alleged.

But instead of jumping straight in, Baez took time to take off her shoes and socks and put her phone aside before taking Katlyn out of the water, prosecutors said.

When EMS workers arrived, Baez lied telling them she’d only left the girl for five minutes, the DA’s office said.

The EMTs were able to revive the girl but she was left with irreversible brain damage from the lack of oxygen and was forced to live on a ventilator and feeding tube for two months, prosecutors said.

The little girl died on May 1 after she became septic, the office said.

Baez was arrested on May 15 and charged with second-degree manslaughter and two counts of endangering the welfare of a child. She pleaded not guilty in court on Tuesday.

“The alleged actions of this defendant were selfish, senseless and heartless,” District Attorney Raymond Tierney said in a statement. “We are going to do everything we can to ensure that justice is served for little Katlyn, whose short life ended too soon.”

Baez is due back in court on May 24.

Suffolk County Legal Aid Society, which is representing Baez, did not return a message.