After the Hearst Corporation, NBC and ABC announced in the summer of 1984 that they would spin off A&E (which occupied the timeslot formerly occupied by the Alpha Repertory Television Service prior to its merger with The Entertainment Channel earlier that year) into a separate 24-hour cable channel and cease transmitting its programming over Nickelodeon's channel space to take better advantage of valuable satellite time, MTV Networks President Bob Pittman asked Nickelodeon general manager Geraldine Laybourne to develop programming to fill the time period that would be vacated (once A&E became a separate channel in January 1985, Nickelodeon simply displayed a test pattern screen after the network signed off). After futile attempts at original program development, Laybourne asked programming and branding consultants Alan Goodman and Fred Seibert of Fred/Alan Inc. (successful as the original branders of MTV, and for Nickelodeon's extensive 1984 rebranding) to come up with programming ideas.

After being presented with over 200 episodes of The Donna Reed Show (a 1950s sitcom which Laybourne despised), Goodman and Seibert conceived the idea of the "first oldies TV network." They modeled the new evening and overnight programming block on the successful oldies radio format, "The Greatest Hits of All Time," and branded the block with their next evolution of MTV- and Nickelodeon-style imagery and bumpers. Head programmer Debby Beece led the team to the name "Nick at Nite" for the new block; a logo originally conceived for the block was based on Nickelodeon's "pinball" logo introduced in 1981, which was discontinued with that network's rebrand. Fred/Alan developed the original logo with Tom Corey and Scott Nash of Boston advertising firm Corey McPherson Nash, creators of the well-recognized Nickelodeon orange logo (Nick at Nite's logo design would maintain a separate visual appearance from its parent network).

Nick at Nite debuted at 8:00 p.m. Eastern Time on July 1, 1985, as a block on Nickelodeon. Its initial programming (running from 8:00 p.m. to 6:00 a.m., seven days a week) was a mix of sitcoms, movies and one drama series, led by Dennis The Menace, and accompanied by The Donna Reed Show, the offbeat comedy Turkey Television (which, like Dennis, also aired on Nickelodeon), and Route 66. A nightly film presentation, branded as the Nick at Nite Movie, aired at 9:00 p.m. Eastern Time through the end of the decade, and included such classic films as the 1947 film The Red House and the 1937 film A Star is Born. The same five-hour block of programs originally repeated from 1:00 a.m. and ran until Nickelodeon began its broadcast day at 6:00 a.m. Eastern Time. As Nick at Nite grew, it would add to its library of shows – branching out to rerun sketch comedy, such as episodes from the early seasons of Saturday Night Live as well as the Canadian series SCTV. It also briefly reran the 1970s mock local talk show Fernwood 2Night. As the years went by, the channel's sitcom library swelled to over a hundred shows. For the channel's 20th birthday celebration in June 2005, TV Land aired an episode from almost every series that had appeared on Nick at Nite.

The Nick at Nite 10th Anniversary logo from 1995. The Nick at Nite logo seen in this screenshot, located within the "0" in "10", is a variant of the logo used for the block from 1992 to August 31, 2002, which in turn was modified from the original logo that debuted on July 1, 1985.
By the early 1990s, Nick at Nite began running a full schedule of programming, with overnight hours filled by a mix of secondary runs of shows airing on its evening schedule and series that were no longer shown on the evening lineup. In 1995, Nick at Nite celebrated its 10th Anniversary with a week-long event, in which the channel aired "hand picked episodes" of almost every series that had aired on Nick at Nite since its July 1985 debut. Each episode was introduced with its history, episode number, and references to the individual program's original run on Nick at Nite. A special 10th Anniversary on-screen bug was shown at the bottom left corner of the screen for 10 seconds once per half-hour show, and was used for the entire 1995 calendar year, much in the same manner as the 20th Anniversary logo in 2005 (in contrast, Nick at Nite did not make any acknowledgment of its 25th Anniversary in 2010).

Nick at Nite logo used from September 1, 2002 to September 1, 2007 (which is an updated version of the 1992 to 2002 design, with a circle as its only background); an orange variant used from 2006 to September 1, 2007.
In March 2004, Nielsen began splitting up Nick at Nite and Nickelodeon in its primetime and total day ratings reports, due to the different programming, advertisers and target audiences between the two services; this caused controversy among executives of some cable channels who believed that this move manipulated the ratings, given that Nick at Nite's broadcast day takes up only a fraction of Nickelodeon's programming schedule.[4] Nickelodeon's and Nick at Nite's respective ratings periods encompass only the hours they each operate under the total day rankings, though Nick at Nite is rated only for the primetime ratings; this is due to a ruling by Nielsen in July 2004 that networks have to program for 51% or more of a particular daypart to qualify for ratings for that daypart.[5]

Nick at Nite logo used from September 1, 2007 to September 28, 2009.
In 2007, the coloring of Nick at Nite's logo was changed from blue to orange, in order to match the coloring of Nickelodeon's logo. On September 1, 2007, the network introduced a new logo based on Nickelodeon's longtime "splat" logo, with the orange "splat" formed in the shape of a waxing gibbous moon – this effectively integrated the Nickelodeon branding onto Nick at Nite for the first time, as the varied logos that were used from its 1985 launch utilized variants of the Futura Condensed font (the 1984 to 2009 Nickelodeon logo designed by Seibert and Goodman used the Balloon typeface) with various shape backgrounds and a small circle with the word "at" (replaced by an "@" symbol overlaid on a circle background in 2002 for visual symmetry, owing to the character's building ubiquity from the Internet and eventually into general pop culture) lodged between and staggering the "I" ' s.

On July 5, 2009, Nick at Nite extended its programming hours to end at 7:00 a.m. seven days a week (the weekend lineup ended one hour earlier from April to June 2010 and from January to May 2011) and to begin at 8:00 p.m. Eastern Time on Sunday through Thursday nights and 9:00 p.m. Eastern Time on Friday nights (the Saturday lineup continues to have a 10:00 p.m. Eastern Time start time due to the presence of the long-running Saturday primetime comedy lineup on Nickelodeon). Nick at Nite's times of operation have changed several times over the years, to at one point (between 1998 and 2000) beginning as late as 9:00 p.m. Eastern Time on Sunday through Thursdays and ending as early as 5:30 a.m. Eastern Time.

Nick at Nite overhauled its on-air appearance on September 28, 2009, as part of Nickelodeon's universal rebranding effort – the new logo, also based on Nickelodeon's logo, stylized the network's name as "nick@nite" (rendered as one word in lower case letters within the new network logo).[6] The network also stopped airing the production closing credits for most of its programs (except for those that have tag scenes during the end credits, and originally some series that aired on the network prior to the rebrand that rejoined the network afterward, such as Full House) and began employing network-uniform closing credits – which Nickelodeon had been utilizing since at least 2000 (both Nick at Nite and Nickelodeon often omit end tag scenes or blooper reels of some shows using this format).