In 1983 Seiko was romantically linked with singer Hiromi Go and there were rumours of an impending engagement. However, Go's traditional values would have required that Seiko give up her singing career to concentrate on raising a family. The top female idol of the 1970s, Momoe Yamaguchi, had followed such a course, but Seiko made headlines by ending her relationship with Go instead. Her break from tradition set a precedent for Japanese women in the 1980s and 1990s to continue their careers even after marriage.

Matsuda has been married three times. She was married to actor Masaki Kanda from 1985 to 1997. Their only child, a daughter named Sayaka Kanda, is also a singer.

Matsuda used to hold the records for the most number 1 singles (25) and most consecutive number 1 singles (24) on the Japan's Oricon charts, for 12 years from 1988 to 2000. Both were surpassed by B'z in late 2000. She held the record for the most number 1 singles (25) by a female singer for 18 years from 1988 to 2006 when Ayumi Hamasaki's "Startin'/Born to Be..." reached number 1, making it her 26th single to top the charts. Matsuda's streak for the most consecutive number 1 singles (24) by a female singer and any soloist was held from 1988-2010 for 22 years. It was then broken by Hamasaki's "L" in September/October 2010. Matsuda also hold records for the most top 10 albums (50) and most number 1 albums. The former is tied by Hamazaki and the latter was broken again by Ayumi Hamasaki. Matsuda was the first Artist in the Oricon history to have a single and an album debut at No. 1 on Oricon Chart in the same week. So far, this has only happened three times.

Matsuda attempted to break into the North American market with an English-language, self-titled album in 1990. She managed to score a hit - "The Right Combination", a duet with boy band New Kids on the Block singer Donnie Wahlberg. The album sales were mediocre, and her follow-up Was it the Future failed to generate any significant sales. In 2002, however, Matsuda's English dance hits "All to You" and "Just for Tonight" managed to reached the Billboard dance chart at No. 8 and No. 2, respectively.

Her second husband was a dentist whom she married in 1998. They divorced in 2000.

In July 2006, Matsuda's compilation album Seiko Matsuda, which consisted of 74 CDs, debuted at number 96, becoming the highest-priced album in the Oricon history at the price of 100,000 yen (about 850 dollars). Hibari Misora, a well-known enka singer from the 50’s held the previous record with her 1989 album Kyō no Ware ni Asu wa Katsu (60,000 yen).

Although some up and coming female Singers like Namie Amuro and Ayumi Hamasaki became successful after the end of the 1980s, most "typical" pop idols during Matsuda’s era disappeared in Japan as the idol golden age began to fade away, except Matsuda, who was still going strong, releasing single after single. She has been a secret idol for subsequent female celebrities such as Shoko Nakagawa who called Matsuda "God" and "My Universe". Japanese voice Actress Nana Mizuki released her cover version of Matsuda's "Akai Sweet Pea" (lit. "Red Sweet Pea") as the B-side of an image song single under the character name Moka Akashiya of the anime Rosario + Vampire on February 14, 2008. There are endless cover version of Matsuda songs and tribute albums being released every year. Among those 'Diamond Eyes', 'Missing You' and 'Akai Sweet Pea' (lit. Red Sweet Pea) and Sweet Memories have been reinterpreted by other artists countless times, including cover performance by Akina Nakamori.

On 5 August 2009, Sony re-released 16 of Matsuda's early albums under the Blu-spec CD format. 13 of them entered Oricon Top 100 Album Chart at the same time, surpassing the record of Hibari Misora (12 albums) and making her the first female Artist to do so.

In a May 2011 Oricon survey crowned her the No. 1 everlasting idol of all time, beating Momoe Yamaguchi (2), Kyōko Koizumi (3), Morning Musume (4) and Akina Nakamori (5).

On June 13, 2012, she announced her marriage to a university associate professor on her official website.

In 2015, Matsuda won the Japanese equivalent of a Grammy Award when she received Best Vocal Performance at the Japan Record Awards, the most prestigious award in the Japan music industry.

After winning the ‘Miss Seventeen’ contest held by a popular magazine in 1978, a sixteen year old girl named Noriko Kamachi from Kukuoka adopted the stage name "Seiko Matsuda" and rose to fame in 1980 as a teen idol, making her debut with the song "Hadashi no Kisetsu" (lit. "Season of bare feet"). Later in the same year, her 3rd single "Kaze wa Aki-iro" (lit. "Wind is autumn color") became the first of her 24 consecutive number 1 hits in Japan. She shattered the Japanese former record of nine consecutive number-ones by popular 70’s music duo Pink Lady. Her consecutive number 1 record ended in 1989 when her 27th single "Precious Heart" was ranked at number-two, behind Tetsuya Komuro's "Gravity of Love". Matsuda gained another number 1 single "Anata ni Aitakute ~Missing You~" (lit. "I want to meet you ~Missing you~") in 1996, which would remained as her last number 1 single till date. The single was certified a million-seller by RIAJ.