Jessica Price, 24, and Angela Price, her mother, both of Morris Close, had pleaded not guilty but were convicted of all charges in total at Luton Crown Court following a trial.
During the trial, the jury heard how both mother and grandmother had continually neglected Imran by failing to provide him with adequate food or drink, as well as causing him unnecessary suffering by failing to provide him with medical aid.
Detective Inspector Alan Page, from the Bedfordshire, Cambridgeshire, and Hertfordshire Major Crime Unit said: “This was an absolutely heart-breaking case which saw the tragic death of an innocent young baby, caused by two people who were meant to care for him the most.
“Baby Imran lost 17 per cent of his body weight in just nine days, showing how dehydrated and malnourished he had become as a result of his mother and grandmother’s neglect. He also had what doctors described as one of the worse cases of nappy rash they had ever seen.
“I am sure that Imran would still be alive today if he had been cared for correctly and I’m pleased that justice has been done in finding those responsible for his death guilty.”
Sentencing for both women is to be held on 25 November.