Arbaeen is one of the most revered holidays on the Shiite calendar marking the end of 40 days of mourning for the death of Imam Hussein, the grandson of the Prophet Mohammed.
At least 80,000 Shiite pilgrims traveled from across the Middle East and Central Asia to join the millions of Iraqi pilgrims who came to Karbala Thursday for the celebrations, the Arab language al-Alam news agency said.
The former regime of Saddam Hussein banned all Shiite religious ceremonies.
Iraqi Vice President Adel Abdul-Mahdi traveled on foot to Karbala to participate in celebrations. It is considered a sign of devotion and humility to make the pilgrimage on foot.
Iraqi snipers and bomb squads patrolled the city throughout the week, and the mayor of Karbala, Okeil al-Khazaaly, said the celebrations "went fine without any violent attacks."
Maj. General Raed Shakir Jawdat, the chief of police in Karbala, told Voices of Iraq Tuesday his forces uncovered around 80 missiles and "thousands" of rounds of ammunition.
Karbala police also used sonar-equipped vehicles to search the area for explosives ahead of Thursday's events.
Sources told the Lebanese Daily Star Thursday there were about 40,000 security personnel, including 3,000 Iraqi national police, deployed in and around Karbala with support of helicopters and aircraft. About 600 female Iraqi security guards were also on hand to search female pilgrims.
About 40 people were killed in Iskandariyah Sunday as a suicide bomber targeting pilgrims traveling to Karbala.