Kirilenko comes after the Nets were rejected by Bojan Bogdanovic and Kyle Korver.
Kirilenko agreed to a two-year contract and will make $3.18 million next season. For 2014-15, he holds a player option.
The deal has led to suspicion among other NBA teams and their owners.
Kirilenko, known as a Swiss Army knife for his versatility, is arguably a much better player than either Bogdanovic or Korver. In Kirilenko's 2013-14 contract with the Minnesota Timberwolves, he would have earned $10 million and a first-round playoff exit.
The most obvious answer answer as to why he would take such a pay cut would be that Nets owner Mikhail Prokhorov and Kirilenko share the same motherland, Russia. Prokhorov is a billionaire who earned much of his money in the unregulated mayhem of post-Soviet Russia.
Some NBA managers have suggested that Prokhorov might be slipping Kirilenko some extra rubles. Similar situations in the past, like that of Blake Griffin and Donald Sterling or LeBron James and Micky Arison, have not been investigated.
The only current owner to be busted for a secret contract was Glen Taylor, a former state-level politician, when the Timberwolves signed Joe Smith to an illegal secret contract.
But those questioning the deal may simply feel threatened by the Russian billionaire's approach to business in the NBA.
Senate Democrats to pull all-nighter on climate change
Susan Sarandon 'very excited' about daughter's pregnancy