Born Grete Andersen in Oslo, Norway, Waitz was a talented young runner, but had difficulty in getting her parents to take her potential profession seriously. However, Waitz ran at the 1972 Summer Olympics in Munich in the 1500 metres, and to support her athletic career she studied at a teachers college.
In her teen years, Waitz won national junior titles in Norway in the 400 and 800 metres. At age 17 she set the European junior record for 1500 m with a time of 4:17 and won a bronze medal at the European Championships in this event in 1974. In 1975 Waitz broke the 3000 metres world record, running 8:46.6 in Oslo. In Oslo a year later she lowered this record with an 8:45.4 effort, then in 1977 she won a gold medal at this distance at the inaugural IAAF World Cup in Athletics meet in Düsseldorf with a personal best time of 8:43.50. Two years later in Montreal she won a silver medal, also in Oslo, she came to her all-time personal best of 8:31.75. Her 4:00.55 career best in the 1500 m, set in Prague in 1978, still stands as the Norwegian national record. Her last race was a victory at 5000 metres in Oslo in June 1982, in which her 15:08.80 was the second best in history, falling only a half second short of the world record set three weeks earlier by Mary Slaney.
It was in 1978 that her association with the New York City Marathon began; she was invited to run there by race co-founder and director Fred Lebow, and in her first appearance she not only won but took a full two minutes off the women's world record. She went on to win the race nine times and broke the world record three years in a row. In all, she lowered the women's world record by nine minutes, taking the standard from Christa Vahlensieck's 2:34:47 down to 2:32:30 in 1978, 2:27:33 in 1979, 2:25:41 in 1980, and finally to 2:25:29, which she ran at London in 1983. Besides her marathon victories in New York and the 1983 World Championships in Helsinki, Waitz also won the London Marathon in 1983 and 1986 (the latter in a personal best of 2:24:54), as well as the Stockholm Marathon in 1988 at 2:28:24 (which as of 2011 is still the Stockholm course record for women).
Waitz enjoyed much success on the road at non-marathon distances as well, including a win at the Falmouth Road Race in 1980, four victories at the prestigious 10-km Peachtree Road Race in Atlanta, five wins at the L'eggs Mini-Marathon in New York, and world road records at 8 km (25:03), twice in the 10-km (31:16 in 1979, then later to 30:59), 15-km (48:01), and 10-mile distances. She further demonstrated her versatility by successfully competing in cross country, earning two bronze medals (1982, 1984) at the IAAF World Cross Country Championships and winning the gold medal five times, (1978–1981 and 1983), tying her with Doris Brown Heritage for most wins in the history of women's International/World Cross Country Championships.
The only significant award she did not win in her career was an Olympic victory. As an up-and-coming 19-year-old in Munich and then a 23-year-old running the 1500 m in Montreal (the longest event allowed for women in the Olympics up until 1984), she competed, but did not medal, in an event that was far short of her specialty. In 1980, Norway was one of the countries that decided to boycott the 1980 Summer Olympics in Moscow. At the 1984 Summer Olympics, she was beaten in the marathon by Joan Benoit, placing second to take the silver medal. In the 1988 Summer Olympics in Seoul, Korea, a bad knee forced her to drop out of the women's marathon just after passing the 18-mile mark. She won a gold medal in the marathon at the 1983 World Championships in Athletics in Helsinki.
Waitz completed her last marathon on 1 November 1992 with her friend Fred Lebow. In celebration of Lebow's 60th birthday, after he was diagnosed with brain cancer in early 1990, they both completed the New York City Marathon with a time of 5:32:35.1500 metres – 4:00.55 – Prague – 03/09/1978
One mile – 4:26.90 – Gateshead – 09/07/1978
3000 metres – 8:31.75 – Oslo (Bislett) – 17/07/1979
15 kilometres – 47:52 – Tampa, FL – 11/02/1984
Marathon – 2:24:54 – London – 20/04/1986
Although not competing at the top level, Waitz still ran in and organised corporate races in which she aimed to give advice and information on distance running and health. She also did charity work, particularly for the CARE International and the International Special Olympics. In June 2005 it was publicly known that she was undergoing treatment for cancer. She also coached Liz McColgan. For more than 25 years, Waitz served as the ambassador for the worldwide JPMorgan Chase Corporate Challenge Series, promoting health and wellness to full-time workers. She provided regular training and motivational tips. Waitz was also a spokesperson for Avon Products.
In August 2009 it was revealed that Waitz had initiated a co-operation between her old sponsor, Adidas, and the cancer care foundation she started in 2007 – "Aktiv mot kreft". The co-operation would mean that the cancer care foundation would get 5% of the proceeds from Adidas' sale of their Grete Waitz and Modern Classics collections. This could be as much as NOK 500 million per year, which would go to the establishment of hospital physical training centres and investment in PET-scanners.
Waitz died of cancer on 19 April 2011, aged 57. Waitz was survived by her husband Jack and her brothers Jan and Arild. The Norwegian government later announced she would be buried with government honor at state expense, the sixth woman in Norwegian history to be given this honor. This was equivalent to a state funeral, although in accordance with her family wishes the ceremony was private.
Waitz is widely acknowledged as helping to promote marathon and long-distance running for women. In Norway she is a sporting legend, with an annual race named after her in her honor. The New York Road Runners club annually sponsors "Grete's Great Gallop," a half-marathon, in her honor.
There is a statue of her in the Norway pavilion in EPCOT at the Walt Disney World Resort. There is also a statue of her outside Bislett Stadium in Oslo, and she has been featured on a set of stamps. In addition, her portrait is featured on the tail of a Norwegian Air Shuttle 787 Dreamliner aircraft.
On 23 November 2008 Waitz was appointed a Knight 1st Class of the Royal Norwegian Order of St. Olav, bestowed by King Harald V of Norway in recognition of her being an important role model. Waitz received the St. Olav's Medal in 1981 and Medal of St. Hallvard in 1989.TheFinalSprint.com's interview with running pioneer Grete Waitz