The family planned to hold a memorial gathering for the toddler on Monday.
Loffley's lawyer Roger Chambers said his client was ``bitterly disappointed'' at the verdict.
"He knew it would be a close-run thing,'' he said.
Loffley maintained his innocence, said Mr Chambers.
The officer in charge of the investigation, Detective Senior Sergeant Kevin Hooper, said police were pleased Loffley has been held accountable for the toddler's death.
Loffley, 29, was charged with killing JJ, who died on November 14 last year in an Orakei house where he lived with his mother Josephine Lawrence and Loffley.
Loffley is due to be sentenced in February.