MTM Enterprises developed the series for NBC, with network chief Brandon Tartikoff commissioning Steven Bochco and Michael Kozoll to write it, giving them unusual creative freedom to innovate on TV drama conventions.

The show was inspired in part by police procedural novels like Ed McBain's 1956 Cop Hater and has been described as 'Barney Miller out of doors'; director Robert Butler also drew on the 1977 documentary The Police Tapes, which used handheld cameras to follow police in the South Bronx.

Barbara Bosson, who was married to Steven Bochco, came up with the idea of structuring the series into four- or five-episode story arcs.

The pilot was produced in 1980 but was deliberately held back to air as a mid-season replacement in January 1981 rather than compete with the fall 1980 premieres.

Although mostly filmed in Los Angeles (on location and at what is now CBS Studio Center in Studio City), the series' opening, closing, and cutaway shots were filmed in Chicago, and the city depicted was intentionally left unnamed, meant as a hybrid of Chicago, Buffalo, and Pittsburgh, partly inspired by Bochco's memories of Pittsburgh's rundown Hill District from his college days.

Producers deliberately obscured clues to the show's setting, such as hiding whether local TV station call letters began with 'W' or 'K', though inconsistencies slipped through, including visible Coors beer bottles (not distributed east of the Mississippi until 1986), a Los Angeles Street sign, California license plates on trucks, and an Illinois state flag in a courtroom scene.

The show's title phrase is spoken only once in the entire series, by Detective Emil Schneider in the first-season episode 'Gator Bait,' said in a mocking tone about two officers he felt were out of their depth.

In the original ending of season one, Officer Joe Coffey was to be killed in a vehicle stop shooting, but producers decided to keep the character alive and re-edited the scene to show him only seriously wounded; he was eventually killed off in season six instead.

Despite rave reviews, the show had dismal ratings in its first season, ranking 87th out of 96 shows and becoming the lowest-rated program ever renewed for a second season at the time, initially picked up for only 10 more episodes before a full order was later approved.

Dennis Franz played two different characters on the show: the corrupt Detective Sal Benedetto in several season three episodes, and later the regular character Lt. Norman Buntz starting in season six, with the two characters designed as doppelgängers.

At the Emmy ceremony where Betty Thomas won Outstanding Supporting Actress, prankster Barry Bremen ('The Great Imposter') rushed the stage claiming Thomas couldn't attend, accepted the award himself, and left before Thomas returned to give her speech after the commercial break.

The show's theme music was composed by Mike Post featuring Larry Carlton on guitar, and it became a genuine hit single, reaching #10 on the Billboard Hot 100 in November 1981 and winning the Grammy Award for Best Pop Instrumental Performance.

The Simpsons episode 'The Springfield Connection' pays tribute to the show by blending The Simpsons and Hill Street Blues theme music, and Southern rock band 38 Special's music video for 'Back Where You Belong' is an affectionate homage that opens with a roll-call scene echoing the show's format.