The FBI's Long Island gang task force and the Suffolk Police department's gang unit made the arrests after an investigation that spanned several months.
The eight are now facing drug, assault and weapons charges.
"This law enforcement effort sends a strong signal to gang members that their actions won't be tolerated," said county executive Steve Levy in a statement.
The arrests came just days after angry Huntington Station residents rallied outside town hall, demanding action against the gangs.
Two alleged gang shootings in Huntington Station this month prompted the public outcry and led some in the community to demand that local officials close a school near where the shootings took place.
Community activists and residents in Central Islip, Brentwood and Wyandanch have also demanded stepped up law enforcement in their communities. At least five have been killed in alleged gang violence in those areas over the last six months.
Some have complained that county executive Levy, now a gubernatorial candidate, has neglected concerns in his home area.
In response, Levy has ordered police to "saturate" the areas, including random traffic stops designed to highlight the increased police presence.