The original blue-and-silver Walkman model TPS-L2 went on sale in Japan on July 1, 1979. In the UK, it came with stereo playback and two mini headphone jacks, permitting two people to listen at the same time (though it came with only one pair of MDR-3L2 headphones).

Where the Pressman had the recording button, the Walkman had a "hotline" button which activated a small built-in microphone (the Pressman), partially overriding the sound from the cassette, and allowing one user to talk to the other over the music. The dual jacks and "hotline" button were phased out in the follow-up Walkman II model.

Some devices were also capable of recording. The highest quality Sony Walkman recording cassette deck was the Walkman Professional WM-D6C. It was introduced in 1984, and was comparable in audio quality with many of the best non-portable cassette decks.

Unusual for a portable device, the Walkman Professional had bright LED recording level meters and manual control of recording levels. It was equipped with quartz direct drive capstan, and amorphous head. Powered by local AC mains or by 4 AA batteries (compared with 2 for most Walkman models), it was widely used by journalists and developed a following among hi-fi enthusiasts; unusual for a consumer-electronics product, it was in production, unchanged, for almost 20 years. One of Henry Rollins' early spoken word CDs was recorded with a Walkman Pro.

Amid fierce competition, primarily from Toshiba (the Walky), Aiwa (the CassetteBoy) and Panasonic, by the late 80s, Sony upped the ante once again by creating the playback-only WM-DD9, launched in 1989 during the 10th anniversary of the Walkman (five years after the WM-D6C) and became the holy grail for a niche group of cassette Walkman collectors.

It is the only auto-reverse Walkman in history to use a two motor, quartz locked, disc drive system similar to high-end home cassette decks to ensure accurate tape speed for both sides of playback (only one motor operates at a time depending on the side of the tape being played). Power consumption was improved by requiring only either one AA battery or one gumstick-type rechargeable, with optional AC adaptor input.

It is also equipped with a tight gap amorphous tape head capable of reproducing the full 20–20,000 Hz frequency range, a gold plated headphone jack, and a 2 mm thick aluminum body. Sony made this model with only sound quality in mind, therefore it contains no gimmick features such as in-line remote control, music search, or LCD readout.

Its only features are Dolby B/C noise reduction decoding, Mega Bass/DBB bass boost, tape type select, and two auto reverse modes.