Krukow attended San Gabriel High School in San Gabriel, California, where he played as a catcher. He was drafted as a catcher by the California Angels in the 32nd round of the 1970 Major League Baseball Draft but did not sign.
Krukow played college baseball for the Cal Poly Mustangs in San Luis Obispo, California. Though his collegiate eligibility was cut short, he still holds the school record for career earned run average at 1.94 and is tied for most shutouts in a season with 5.
Krukow was drafted by the Chicago Cubs in the 8th round of the 1973 draft. Krukow played Major League baseball for the Chicago Cubs (1976–1981), the Philadelphia Phillies (1982) and the San Francisco Giants (1983–1989). He batted and threw right-handed.
Krukow had a solid career in the major leagues. In 1982, after six years with the Cubs, he was dealt to Philadelphia for pitchers Dickie Noles and Dan Larson and outfielder Keith Moreland.
The right-handed starter was second only to Steve Carlton in wins, posting a 13-11 record and an impressive 3.12 ERA, but despite this success, the Phillies sent Krukow, Mark Davis and Charlie Penigar to the San Francisco Giants in December 1982 in a trade for Joe Morgan and reliever Al Holland. The trade helped Philadelphia win the National League pennant in 1983, but it also gave San Francisco two arms that would become a big part of the Giants' success in the late 1980s.
Although known as a starter, Krukow earned his only career save on August 31, 1984, pitching to just one batter (the Phillies' Sixto Lezcano), inducing a game-ending groundout, therefore preserving a 6–5 Giant victory.
Krukow's best season was in 1986, posting a record of 20-9 with a 3.05 ERA pitching for the San Francisco Giants. Krukow finished third in that year's NL Cy Young Award voting behind Mike Scott and Fernando Valenzuela. Krukow was selected to the National League All-Star team that season. He was awarded the Willie Mac Award in both 1985 and 1986 honoring his spirit and leadership. In 1987, Krukow helped lead the Giants to their first division championship in 16 years.
On June 30, 1989, Krukow underwent arthroscopic surgery to repair a torn rotator cuff in his pitching shoulder after spending parts of three seasons on the disabled list for what was believed to be bursitis. He retired in March 1990. In his 14-season career, Krukow posted a 124-117 record with 1,478 strikeouts and a 3.90 ERA in 2190.1 innings pitched.
After his playing career, Krukow became a radio and television sportscaster. Krukow began broadcasting as an occasional color analyst for KNBR radio in 1990 and became a full-time broadcaster in 1994. He is a seven-time Emmy award winner. "Kruk," who was named as the starting right-handed pitcher to the 1980s Giants All- Decade Team in a vote by Bay Area media in 1999, is noted for his deep knowledge of the game and tremendous sense of humor. He is known for his detailed scouting reports on umpires' strike zones. He is often teased by his broadcasting colleagues throughout the major leagues for having "majestic hair".
Part of the San Francisco Giants broadcasting team, Krukow is half of the duo dubbed "Kruk and Kuip," (pronounced "Kruke" and "Kipe") along with partner Duane Kuiper, a former Giants teammate. Krukow and Kuiper tape a game-day commentary ("Kruk and Kuip on baseball") for KNBR radio as part of the Giants' pre-game radio coverage. Notably, although Krukow was a pitcher and Kuiper was a position player, Krukow has five career home runs, four more than Kuiper (who managed only one in his career despite having over 3,000 at-bats).
Krukow has a few "Kruktionary" catchphrases, including: "Grab some pine, meat"; "Just another, ha ha ha ha, laugher!" (after a nail-biter win); and "I wanna get that!", the last of which is associated with a product endorsement.
Krukow and Kuiper can be heard as the commentators in Electronic Arts video games MVP Baseball 2003, 2004 and 2005. They include Krukow's familiar "grab some pine, meat" quote.
Until the summer of 2014, Krukow and his wife Jennifer resided in San Luis Obispo, California, but they moved to Reno, Nevada to be closer to their grandchildren. They have five adult children, Jarek, Baker, Tessa, Chase and Weston. He is a talented musician, and proficient in the guitar, the mandolin, the banjo, and the ukulele.
In July 2014, Krukow revealed he was suffering from inclusion body myositis (IBM). His condition was known to the Giants and many of his fellow broadcasters, but he kept the condition a secret from the general public until then. Krukow first noticed that he was having problems about 10 years earlier, when he had lost about 100 yards (90 m) off his golf drive. According to sportswriter Steve Fainaru, Krukow "blew it off... for years", but "secretly feared he had amyotrophic lateral sclerosis, Lou Gehrig's disease". Finally, in 2011, he saw the Giants' team neurologist, who referred him to a neuromuscular specialist who in turn diagnosed him with IBM. The disease, which mainly affects the quadriceps and hand muscles, is not life-threatening, but now requires him to use a cane; eventually, Krukow will have to use a walker and/or a scooter. Because of increasing hand weakness that limits his ability to play stringed instruments, he has recently taken up the drums, which require a different set of muscular movements. Krukow plans to continue broadcasting for the foreseeable future, but in 2017, he announced that he would reduce his schedule to 120 games a season, only working road games west of Denver, except for postseason games.