Hannah Price, 25, went into pubs and betting shops to "prey" on the emotions of the public by posing as a family friend of the little girl.
Price claimed she was collecting cash to cover the funeral costs of Amelia Brooke Harris, who was found dead at a property in Trealaw, near Tonypandy on June 8 this year.
The four-year-old's mother, Carly Ann Harris, has been charged with murdering her daughter and will stand trial in December.
Merthyr Crown Court heard on Friday that Price went to businesses in Treorchy and Pontypridd, communities near to Trealaw, just a month after Amelia's death and posed as a family friend.
Price used a black book and a clipboard to record the donations in an effort to look legitimate.
She then used the cash she collected to fund her drug habit, which included heroin.
Members of the public became suspicious of her and reported her to police, who later charged her with two counts of fraud.
Prosecutor Rachel Knight said: "Price said she was 'clucking' and would do anything to get drugs."
Ms Knight said Price was also charged with burglary after she gained access to a home using the same story before stealing a wallet.
The total amount of cash Price took in donations and from her burglary was between £30 and £50.
Judge Richard Twomlow called Price's actions "callous" and "disgraceful" as he sentenced her for four counts of fraud, one count of attempted fraud and burglary.
He said: "You claimed to be a friend of a family who lost a very young child.
"Feelings in the community were high and you took advantage of that.
"The way you preyed on people's emotions is disgraceful.
"It's hard to imagine a more callous fraud than this."
Price, from Treorchy, was sentenced to three years and three months in jail.
After the hearing Mani Ranauta of the CPS said: "Price took advantage of the tragic circumstances surrounding the death of a young child in order to fuel her drug addiction.
"Her actions were callous and calculated.
"She also took advantage of the same situation to gain access to someone's home, stealing while pretending to do a good deed.
"The support of the local community allowed the CPS to build a strong case against Price, resulting in guilty pleas to these crimes."