Carmelo and La La Anthony spent part of La La's birthday Monday visiting the home of a slain 15-year-old boy to provide condolences and gifts to the murdered child's family.
Lesandro Guzman-Feliz was brutally stabbed to death after being dragged out of a corner store last week.
When La La was contacted by the boy's sister and informed he was a huge Melo fan ... she brought the NBA superstar right to his fam's doorstep.
"This is what I wanted to do for my birthday today," La La said of the trip.
"Thank you to the gram for connecting me to this family. I wanted to offer our love and support to Lesandro 'Junior’s' family. His sister reached out and told me he loved Melo."
"So I asked Mel to go with me. I can’t imagine this type of pain and sadness. His family is strong and may God bless them forever."
In addition to signed jerseys and sneakers ... La La says she and Carmelo did far more than that for the family -- and urged others to donate.
"This family will be in my heart forever," she wrote. "#justiceforjunior #justiceforjunior."