The heightened security measures in place in Istanbul, as well as in other cities, were not enough to prevent an attack on one of Istanbul's most exclusive night spots on the banks of the Bosphorus.
Among those killed in the attack, 16 of them were foreign.
The suspected assailant was still on the run.
Elsewhere, hundreds of thousands congregated near the Brandenburg Gate in Berlin to see the fireworks display and take part in the festivities as Germany saw in 2017 amid heightened security measures.
Police in the western German city of Cologne carried out screening and security checks on people arriving to the city by train as part of measures to prevent a repeat of the sexual assault and robbery that tainted last year's New Year's Eve celebrations.
Between 500,000 and 600,000 people gathered to ring in the New Year on the Champs Elysees in the French capital, under the watch of some 1,700 security officials.
Safety barriers and concrete blocks were placed to stop vehicles veering off into pedestrian zones.
After suffering its worst terror attack in its history in 2016, Brussels welcomed the New Year without any incidents, with between 40,000 and 50,000 people congregating for the celebrations.
An Italian explosives expert was injured in Florence when a suspect package reportedly exploded.
Police found the package at about 5 am local time in front of a bookstore, and proceeded to isolate the area.
Officials were investigating another suspicious package in Rome, while security in the Vatican was ramped up for Pope Francis' first mass of the year.
The United Kingdom celebrated amid heightened security measures in London and in the cities of Edinburgh and Manchester, with police reporting no incidents.
And in Madrid, New Year festivities took place with no incidents, but brought a lot of trash to the streets and main party square of Sol.
Madrid authorities had reinforced police presence, banned trucks heavier than 3,500 kilograms (2,200 pounds), and installed obstacles, such as planters, bollards and heavy vehicles as preventative measures.