With a long history, Bell Labs is credited with the development of radio astronomy, the transistor, the laser, the photovoltaic cell, the charge-coupled device (CCD), information theory, the Unix operating system, and the programming languages B, C, C++, S, SNOBOL, AWK, AMPL, and others, throughout the 20th century.

By 1939, the Summit, New Jersey, chemical laboratory was nearly 10 years established in a three-story building conducted experiments in corrosion, using various fungicides tests on cables, metallic components, or wood.

These devices were used for marine, aircraft, and police services as well as the location performed precision frequency-measuring apparatus, field strength measurements, and conducted radio interference.

A 2012 article expressed doubt on the success of the newly named Bell Works site,[20] but several large tenants had announced plans to move in through 2016 and 2017.

[39] Bell Laboratories was, and is, regarded by many as the premier research facility of its type, developing a wide range of revolutionary technologies, including radio astronomy, the transistor, the laser, information theory, the operating system Unix, the programming languages C and C++, solar cells, the charge-coupled device (CCD), and many other optical, wireless, and wired communications technologies and systems.

In 1931 and 1932, the labs made experimental high fidelity, long playing, and even stereophonic recordings of the Philadelphia Orchestra, conducted by Leopold Stokowski.

The British wartime codebreaker Alan Turing visited the labs at this time, working on speech encryption and meeting Claude Shannon.

During World War II, Emergency Technical Committee – Quality Control, drawn mainly from Bell Labs' statisticians, was instrumental in advancing Army and Navy ammunition acceptance and material sampling procedures.

[73] The research of Philip W. Anderson into electronic structure of magnetic and disordered systems led to improved understanding of metals and insulators for which he was awarded the Nobel Prize for Physics in 1977.

In the 1970s, major central office technology evolved from crossbar electromechanical relay-based technology and discrete transistor logic to Bell Labs-developed thick film hybrid and transistor–transistor logic (TTL), stored program-controlled switching systems; 1A/#4 TOLL Electronic Switching Systems (ESS) and 2A Local Central Offices produced at the Bell Labs Naperville and Western Electric Lisle, Illinois facilities.

It was a programmable bitmap graphics terminal using multi-layers of opened windows operated by a keyboard and a distinguished red-colored three-button digitized mouse.

[78] The launching of the Bell Labs Fellows Award started in 1982 to recognize and honor scientists and engineers who have made outstanding and sustained R&D contributions at AT&T with a level of distinction.

In 1982, fractional quantum Hall effect was discovered by Horst Störmer and former Bell Laboratories researchers Robert B. Laughlin and Daniel C. Tsui; they consequently won a Nobel Prize in 1998 for the discovery.

Also in 1984, a divestiture agreement signed in 1982 with the American Federal government forced the breakup of AT&T, and Bellcore (now iconectiv) was split off from Bell Laboratories to provide the same R&D functions for the newly created local exchange carriers.

[83] Arthur Ashkin invented optical tweezers that grab particles, atoms, viruses and other living cells with their laser beam fingers.

In the late 1980s, realizing that voiceband modems were approaching the Shannon limit on bit rate, Richard D. Gitlin, Jean-Jacques Werner, and their colleagues pioneered a major breakthrough by inventing DSL (digital subscriber line) and creating the technology that enabled megabit transmission on installed copper telephone lines, thus facilitating the broadband era.

The operating system Inferno, an update of Plan 9, was created by Dennis Ritchie with others, using the then-new concurrent programming language Limbo.

Lucy Sanders was the third woman to receive the Bell Labs Fellow award in 1996, for her work in creating a RISC chip that allowed more phone calls using software and hardware on a single server.

[87] 2000 was an active year for the Laboratories, in which DNA machine prototypes were developed; progressive geometry compression algorithm made widespread 3-D communication practical; the first electrically powered organic laser was invented; a large-scale map of cosmic dark matter was compiled; and the F-15 (material), an organic material that makes plastic transistors possible, was invented.

Magaly Spector, a director in INS/Network Systems Group, was awarded for "sustained and exceptional scientific and technological contributions in solid-state physics, III-V material for semiconductor lasers, Gallium Arsenide integrated circuits, and the quality and reliability of products used in high speed optical transport systems for next generation high bandwidth communication."

Eve Varma, a technical manager in MNS/Network Systems Group, was awarded for her citation in "sustained contributions to digital and optical networking, including architecture, synchronization, restoration, standards, operations and control."

A separate company, LGS Innovations, with an American board was set up to manage Bell Laboratories' and Lucent's sensitive U.S. government contracts.

This is the first period of growth following many years during which Bell Laboratories progressively lost manpower due to layoffs and spin-offs making the company shut down briefly.

Martin J. Glapa, a former chief Technical Officer of Lucent's Cable Communications Business Unit and Director of Advanced Technologies,[97] was presented by Alcatel-Lucent Bell Labs President Jeong H. Kim with the 2006 Bell Labs Fellow Award in Network Architecture, Network Planning, and Professional Services with particular focus in Cable TV Systems and Broadband Services having "significant resulting Alcatel-Lucent commercial successes."

[102] Gee Rittenhouse, former Head of Research, returned from his position as chief operating officer of Alcatel-Lucent's Software, Services, and Solutions business in February 2013, to become the 12th President of Bell Labs.

[104] On May 20, 2014, Michel Combes, CEO of Alcatel-Lucent, announced the opening of a Bell Labs location in Tel Aviv, Israel by summer time.

[106] In 2014, Eric Betzig shared the Nobel Prize in Chemistry for his work in super-resolved fluorescence microscopy which he began pursuing while at Bell Labs in the Semiconductor Physics Research Department.

[110] In September 2016, Nokia Bell Labs, along with Technische Universität Berlin, Deutsche Telekom T-Labs and the Technical University of Munich achieved a data rate of one terabit per second by improving transmission capacity and spectral efficiency in an optical communications field trial with a new modulation technique.

[113] In 2018, Arthur Ashkin shared the Nobel Prize in Physics for his work on "the optical tweezers and their application to biological systems"[84] which was developed at Bell Labs in the 1980s.

The Bell Laboratories Record was a principal house organ, featuring general interest content such as corporate news, support staff profiles and events, reports of facilities upgrades, but also articles of research and development results written for technical or non-technical audiences.