Grainger began in 1993 with the rowing, she appeared first time in 1997 at at World Rowing Championships and won the bronze medal with the British Eighth, the first world championship medal for a British woman rollercoaster ever. Grainger moved during her long career several times between belt boats and sculling boats back and forth. So she joined in 1998 at the World Cup in one of 1999 in the quadruple sculls. In 2000, she won her first World Cup race in the quadruple sculls. At the Olympic Games in Sydney in 2000, the British foursome finished behind the German boat to second place and thus won the first Olympic medal for the British woman rowing.
In the World Cup season 2001 Grainger met with Catherine Bishop in two without coxswain and also won the race in Vienna, at the World Championships, she reached both the two and to the aft the finals, but remained without a medal. 2002 Grainger was again active in the quadruple sculls, but werpasste also a world championship medal. 2003 Grainger took the World Cup along with Bishop once each of the first, second and third place, won at the world championships before the two boats from Belarus and Romania. In the World Cup in 2004, the two repeated their three podiums in the Olympic final won the Romanians Georgeta Damian and Viorica Susanu before the two British women and the White Russians.
2005 Grainger returned to the sculls, who dominated the World Cup season with two wins and a second place and was victorious at the World Cup regatta. 2006 remained the umbesetzte made only one of four in the World Cup and unbeaten at the World Championships; the following year, which reached again only with a boat rower added two World Cup victories and a second place, which brought World Cup regatta for Frances Houghton and Katherine Grainger third title in a row. In the Olympic season in 2008 the boat remained unchanged personnel, but only won the first World Cup race in Lucerne won the Chinese women before the Americans and the British are coming. In the Olympic regatta in Beijing, the Chinese women were able to win on home soil, Katherine Grainger won the third Olympic silver medal.
2009 Grainger returned after eleven years in the one back and won the first World Cup race, but missed the other two races in fourth podium finish. At the World Championships only the Belarusian rower Ekaterina Karsten Grainger before reaching the destination. 2010 dared Grainger from all World Cup races in a double start double sculls and quadruple sculls, won five races and finished only once in the quadruple sculls second place. At the World Championships, she launched only in the double sculls and won the title with Anna Watkins. 2011 remained Watkins and Grainger in two World Cup races and victorious at the World Championships, in 2012, they won all three World Cup regattas and the Olympic final.
Grainger grew up in Aberdeen and is effective for the Edinburgh 's St Andrew Boat Club at. She completed a law degree at the University of Edinburgh and a Masters degree in Medical Law at the University of Glasgow, she earned her doctorate at King's College London. In 2006 she was appointed as member and 2013 the Commander of the Order of the British Empire.
- 2000: 2nd place in the quadruple sculls ( Guin Batten, Gillian Lindsay, Katherine Grainger and Miriam Batten )
- 2004: 2nd place in two without ( Catherine Bishop and Katherine Grainger )
- 2008: 2nd place in the quadruple sculls ( Annie Vernon, Debbie Flood, Frances Houghton and Katherine Grainger )
- 2012: 1st place in the double sculls (Anna Watkins and Katherine Grainger )