Born in Piatra-Olt, Raț began his football career when he joined the local team Rapid Piatra-Olt aged seven in a team trained by his father. In the summer of 1994, Raț went on a trial with Universitatea Craiova. He impressed coach Anghel Mităchescu and joined the club's youth system at age 13. When Mităchescu found out that he was going to be released from his duties by club president Rodion Cămătaru, he transferred the entire junior squad at the Divizia B side Constructorul Craiova. Raț's career for Constructorul, however, ended shortly after due to the club's financial problems, in 1995. In the winter of that year, Raț was noticed by Tudorel Stoica, who attended a futsall tournament held in Balș. Stoica wanted Raț to join Steaua București's youth system. Despite both Stoica and youth coach Bujor Hălmăgean being impressed by the young player, Raț never joined Steaua because according to his father, the club refused to pay the youth, Raț being forced to support himself in Bucharest. Taking advice from his former coach Mităchescu, Raț joined Sporting Pitești, the team trained by former international player Nicolae Dobrin. In his first match, Raț was substituted for the last 10–15 minutes of the game after he had scored five or six goals. On 2 September 1996, after being noticed by Silviu Stănescu, Raț joined Divizia B side Cetatea Târgu Neamț. Despite being only 15 years old, Raț trained with the senior squad. On 19 November, the arrest of Cetatea's main sponsor led to the dissolution of Cetatea Târgu Neamț. Raț getting the chance to play only two matches for the juniors of Cetatea. He later rejoined Sporting Pitești. in 2011 In May or June 1998, Mircea Lucescu noticed Raț, and he signed his first professional contract with Rapid București on 26 June. Raț started his professional career with Romanian Premier League side Rapid București in 1998. In 2003, he was signed by Ukrainian club Shakhtar Donetsk, where he became a key player. He played the whole game as Donetsk won the 2009 UEFA Cup Final.
On 21 May 2013, Raț signed for English Premier League club West Ham United on a free transfer on a one-year contract, with the option to extend it. His West Ham debut came on 27 August 2013 in a League Cup game against Cheltenham Town in which West Ham won the game 2–1. On 31 January 2014, Raț was released from his contract with West Ham by mutual consent. He had played 20 games in all competitions without scoring.
On 8 February 2002, Raț was called up to the Romanian national teamfor the first time. Five days later, he made the starting lineup in his full debut in a Friendly against reigning world and European champions France. Raț played his first official match on 12 October, in a Euro 2004 qualifier match against Norway, playing as a left midfielder. Following the rise of Cristian Chivu in becoming first-choice in central defence, Raț became the first-choice left back for Romania. On 28 April 2004, Raț scored his first goal for the national squad in a 5–1 win against Germany in the worst away defeat for Germany in the past 65 years. On 31 May 2014, Raț scored only his second goal for Romania, but it was the winning goal in a 1–0 victory against Albania in a match played in Yverdon-les-Bains, Switzerland. In 2008, Raț made the squad for the UEFA Euro 2008 tournament. He helped Romania to a 0–0 draw against previous FIFA World Cup finalists France and a 1–1 draw against world champions Italy in the so-called "group of death". Romania, however, were eliminated after a 2–0 loss to the Netherlands. Raț earned his 100th cap for Romania on 14 October 2014 in a 2-0 victory away to Finland in UEFA Euro 2016 qualifying.
