The president crossed the bridge driving the Kamaz truck.
"It is particularly cynical that its opening is happening on the eve of the latest anniversary of the deportation of the Crimean-Tatar people by the Stalin regime".
The annexation of the peninsula in 2014 was condemned by Kiev and the West as an illegal land grab.
The construction of the Kerch bridge illegally, and Russia's attempts to legitimize the temporary occupation of the Crimean Peninsula - in vain.
The construction of the bridge over the Kerch Strait between the Black and Azov seas started in 2015 following the incorporation of the former Ukrainian republic in 2014 and consequent deterioration of relations between Moscow and Kiev.
"I welcome the formal decision of the EU Council to impose sanctions against five individuals responsible for the unlawful conduct of the presidential elections in the temporarily occupied Crimea and Sevastopol", - he wrote.
The Russian leader, who was re-elected for a fourth Kremlin term in March extending his long rule, then pledged to build more of "such projects" across Russia.
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After doing that, they were sent over to a foreign call center where they would be sold on timeshare packages by a real phone operator.
Ukraine has condemned the project, which cost 228 billion rubles ($3.7 billion). "Many didn't believe these plans were possible", Kremlin spokesman Dmitry Peskov told reporters on a conference call on Tuesday ahead of the ceremony.
"Putin initiated this project himself".
"Today, both in a practical sense and from a symbolic point of view, is an extremely important day", he added.
On Tuesday Putin drove an orange Kamaz truck across the bridge as he opened the road to auto traffic.
Originally, the bridge was expected to be built before 2018 and put into operation in the summer of 2019.
At the other end of the 19-kilometer bridge, in Crimea, Putin attended a brief open air show. He was hit with sanctions by the United States for his proximity to Putin and by the European Union for being among those accused of undermining Ukraine's territorial integrity.