Born in Cascade, Iowa, Faber started well in the minor leagues, pitching a perfect game in 1910; but he developed a sore arm in his early 20s, and as a recourse began using the spitball in 1911. He broke into the major leagues in 1914, starting 19 games and relieving in another 21, and posted a respectable 2.68 ERA while winning 10 games and saving a league-leading 4 others. Through the 1910s he would vary between starting and relieving for a team which enjoyed a wealth of pitching talent. In his 1915 season, he won 24 games to tie for 2nd in the American League behind Walter Johnson, and led the league with 50 appearances. In one game that season, he pitched a 3-hitter with only 67 pitches.

In 1917 he had a fair record of 16-13, and at one point started - and won - three games in two days; but he saved his best work for the World Series against the New York Giants. After winning Game 2 in Chicago but losing Game 4 on the road, he came into Game 5 (at home) in relief and picked up the win as the Sox came back from a 5-2 deficit in the 7th inning to win 8-5. Faber came back two days later to go the distance in the clinching Game 6 at the Polo Grounds, picking up his third win of the Series by a 4-2 score.

After spending most of 1918 in the Navy due to World War I, he returned in 1919 only to develop arm trouble, finishing with a 3.83 ERA - the only time in his first nine seasons he posted a mark over 3.00. Those problems, along with a case of the flu possibly related to the epidemic, prevented him from playing in the scandal-torn World Series against the Cincinnati Reds.

Faber then enjoyed the greatest success of his career in the early 1920s. The Live Ball Era was beginning, but he was among the pitchers who made the most successful transition. The spitball was phased out after the 1920 season, with Faber one of the 17 pitchers permitted to use it for the remainder of their careers; and he took advantage of Comiskey Park's spacious dimensions, surrendering only 91 home runs - barely one homer per month - from 1920 to 1931. He was one of only six pitchers to win 100 or more games in both the "dead ball" (through 1920) and live ball eras.

From 1920-22, he posted win totals of 23, 25 and 21, leading the league in ERA ('21-'22), starts ('20), innings ('22), and complete games ('21-'22). He was also among the league leaders in strikeouts each year, while pitching at least 25 complete games and over 300 innings. But the decimation of the team in the wake of the Black Sox scandal, particularly on offense, made winning on a consistent basis increasingly difficult. After being one of the top teams in the league with a powerful offense in the late 1910s, the White Sox had only two winning seasons in his last 13 years, never finishing above 5th place. His 1921 season, going 25-15 for the post-scandal team that limped to a 62-92 finish, is particularly remarkable; from 1921 to 1929 his record was 126-103. Despite the widespread hitting of the era, he did not post an ERA over 3.88 until he was 41. Perhaps his last great performance was a one-hitter at age 40 in 1929.

In his last few seasons, Faber again returned to relief pitching, coming out of the bullpen 96 times between 1931 and 1933. He ended his career at age 45 with a 254-213 career record, a 3.15 ERA and 1471 strikeouts. He holds the White Sox franchise record for most games pitched, and held the team records for career wins, starts, complete games and innings until they were later broken by Ted Lyons. He returned as a White Sox coach for a few seasons, and later worked on a Cook County highway surveying team until he was past 80.

Faber was inducted into the Baseball Hall of Fame in 1964.

He died in Chicago at age 88. Urban Faber was interred in Acacia Park Cemetery, Chicago.