The cunning ruse failed after guards spotted the balls rolling around the prison yard as two men on motorbikes sped off.
They opened up the old footballs to find 10 smartphones in each.
The incident happened around midday on Sunday at Uruguaiana prison in the southern state of Rio Grande do Sul.
The men who threw the balls over the prison wall have yet to be apprehended.
Brazilian police issued pictures today of the mobiles that had been placed inside the footballs before they were sewn back up.
Last year a drone was used to try to smuggle a package into the grounds of Bedford prison.
Charlotte Millward, a 35-year-old mum-of-two, was given a six-month suspended prison sentence after being spotted reaching into her bra and handing 10 tablets to her boyfriend during a visit to Holme House Prison, Stockton.
Inmates at HMP Shotts in Lanarkshire were banned from receiving their children”s drawings by post after powered Valium was found in the paint.
Staff discovered the drug had been painted onto children”s artwork which prisoners would then cut up and eat.
In Sweden a man was once caught firing contraband goods from a bow and arrow which were intended to help one of the prisoners escape.
Last November prison chiefs in Brazil captured a mouse inmates used as a drugs courier to bring them cocaine and cannabis.
The animal was trained to move between wings at Barra da Grota Prison in the city of Araguaina, northern Brazil, with the narcotics tied to a piece of cord attached to its tail.