Targeted by the sanctions were Charles Ble Goude and Eugene Djue, two leaders of the nationalist "Young Patriots" loyal to Ivorian President Laurent Gbagbo, who were blamed for anti-UN disturbances last month in the West African nation.
The council's sanctions committee headed by Greece's UN envoy Adamantios Vassilakis said Mr Ble Goude and Mr Djue made repeated public statements advocating violence against UN personnel and installations as well as against foreigners.
The two pro-Gbagbo officials also impeded the operation of the 7,000-strong UN mission in Ivory Coast (ONUCI) and of the 4,000-strong French military contingent backing it, the panel said.
Also hit by the sanctions, in an apparent bid to show even-handedness, was Martin Kouakou Fofie, a commander among rebel forces holding the north of the former French colony. He was also deemed an obstacle to the work of ONUCI and French forces.
The committee said forces under Commander Fofie engaged in "recruitment of child soldiers, abductions, imposition of forced labor, sexual abuse, arbitrary arrests and extra-judicial killings" in violation of human rights and humanitarian law.
The sanctions were to have taken effect at 10 am (1500 GMT) Tuesday but the official announcement was delayed for bureaucratic reasons at the request of some delegations, Mr Vassilakis said.
The list of targets was officially submitted by France, Britain, Denmark and Slovakia to Mr Vassilakis Friday, and the sanctions were to go into effect if no council member objected within 48 hours.
The sanctions had been called for under the 2004 Security Council
Resolution 1572, but implementation was delayed so as not to hamper an African Union mediation in the Ivorian crisis.
They were designed to punish individuals deemed responsible for obstructing the peace process, incitement to hatred or violations of human rights and the arms embargo imposed on Ivory Coast.
All UN member states are required to enforce the sanctions against the three Ivorian individuals.
The sanctions came in response to four days of anti-UN protests by Gbagbo loyalists last month after an international mediation group ruled that the Ivorian parliament should be dissolved because its five-year term had expired in December.
On January 27, Mr Gbagbo, saying he was acting in concert with transition Prime Minister Charles Konan Banny, declared that the legislature would remain in place "with all its powers." The opposition dismissed the announcement as "null and void."
Anticipating a fresh outbreak of unrest by pro-Gbagbo militiamen once the sanctions are imposed, the Security Council on Monday authorized a 200-strong mechanized unit from the UN mission in Liberia to reinforce the UN mission in Ivory Coast (ONUCI) until late March.
A Western diplomat said the reinforcement for the UN mission in Ivory Coast, a former French colony, would involve 200 Nigerian soldiers, 14 armoured vehicles and 18 support vehicles from the 17,772-strong UNMIL.
Ivory Coast has been divided since fighting broke out in 2002 between Mr Gbagbo's government and insurgents who control the largely Muslim north of the country.