The 19-year-old claimed he was pressured into working for the Custom House gang when he was arrested at a property in Sherborne, Wiltshire, last year.
He was part of so called “cuckooing” operation where gangs set up shop in the homes of vulnerable individuals.
The midfielder said he was approached while playing for League One side AFC Wimbledon and felt he had no choice to because he felt “threatened”, Snaresbrook Crown Court heard.
He helped to move gang members into the home of a woman who felt powerless to resist them.
Police raided the property in School View Close, Sherborne on 1 June 2016 where they arrested Toonga, the court heard.
He was caught with three wraps of cocaine, 29 wraps of heroin, £700 and mobile phones with text messages ‘demonstrating his considerable involvement.’
One message sent by Toonga read: “I will do the bagging up.”
Prosecutor Tom Edwards said Toonga was fully aware of the details of the operation, adding: “Clearly this is a case of cuckooing where a house is occupied.
“Certainly, he had a managing function within the chain, motivated by his financial gain.”
Toonga admitted to possessing with intent to supply class A drugs on 7 February, and he was also charged with failing to surrender to police after he was bailed.
He had broken his leg in November 2016 and “forgot” about going to the police station, the court heard.
A further court hearing was set earlier in the year to determine his specific involvement in the drugs operation before he sentencing.
In giving evidence, Toonga told the court his leg was broken by gang members furious at him for admitting involvement.
But Judge Murray Shanks said Toonga ‘did not put any flesh on the bone’ and gave ‘unconvincing evidence’.
“You are not telling the truth,” he said.
He added: ‘You did look set to enjoy a footballing career, but that was halted with these actions.
‘I am of the view that these offences are so serious that only an immediate custodial sentence is suitable.’
Toonga, who sat in the dock wearing a dark green Nike tracksuit flanked by two dock officers, sat expressionless as the sentence was passed.
He was supported by his mother and brother in the public gallery.
In his youth career, Toonga was on the books for Arsenal, who he joined as an eight-year-old.
He has also played for Cardiff and Southampton, and made four professional appearances for AFC Wimbledon in the 2015/16 season.
Toonga, of Heathway, Dagenham, admitted two counts of possession with intent to supply a class A drug and one count of failing to surrender custody.
Toonga was also handed a three-year criminal behaviour order with three conditions – that he is not to enter Wiltshire accept for passing through, not to have more than one handheld device after release and not to associate with other members of the gang.