The boy was arrested at an address on the northside of the city on Tuesday afternoon, and was detained under section 4 of the Criminal Justice Act.
He was taken to Bridewell Garda Station for questioning, where it is understood he was quizzed about the supply of the synthetic drug, U47700.
Gardaí confirmed the arrest was made arising out of their investigation into the death of Michael Cornacchia, 16, in the Deermount area of the city on Monday.
Michael was found unresponsive at home by his mother, and was pronounced dead at the scene.
Tests on a powder substance found by gardaí at his home identified it as U47700 — a potent synthetic opiate that looks like cocaine.
While toxicology test results are awaited, it is suspected Michael died after consuming a quantity of the drug.
If it is confirmed the drug caused or contributed to his death, he would be the first Irish victim of a drug linked to 90 deaths in the US.
The HSE issued a public health warning about the drug on Tuesday night.