Brambles was born in Essex, England and grew up in Ayrshire, Scotland, where she went to sencondary school at Ayr Academy in Fort Street, Ayr. She also began her radio career on local radio station West Soundin Ayr when she was 19.
She then joined Capital Radio as its youngest DJ, and after a year on the evening show joined the BBC in 1988 as the first female presenter to get her own prime time show on the national pop network BBC Radio 1. She took on the Radio 1 early show, initially at weekends, before graduating to the weekday equivalent. She also joined her colleagues on the Top Of The Pops presentation roster. When Sybil Ruscoe left her role asSimon Mayo's weather and travel reporter, Brambles took over that slot, thereby keeping her on air every day over two separate programmes. On her own shows she sometimes worked standing up in order to maintain a more "live" feel, claiming she found it difficult to keep her demeanour lively enough if she was seated. The combination with Mayo worked well but a minor revamp in 1990 saw Brambles progress to a 90-minute drivetime show and then, when Gary Davies went to weekends, promotion to the important lunchtime slot.
In 1990 she married a Scotsman named Jim Sherry and left BBC Radio 1 in 1994 to move to the United States, where she lived for 11 years. The marriage ended in 1999. There was a plan to make her an American showbiz reporter for the BBC but this never transpired. Instead she re-branded herself as the more maturely-spelt Jackie Brambles, and entered American broadcasting in San Francisco, California as a news radio morning anchor and occasional television news anchor for the CBS network. She also worked as a media consultant to several high profile companies in Silicon Valley, including Intel, Oracle and Sony. Following a move to Los Angeles, California in 1999, she took on the role of foreign correspondent for GMTV, interviewing almost every major star in Hollywood as well as covering major news events including two presidential elections and the events of 9/11.
Six months after returning to the UK in 2005, Brambles married David Todd, who works in financial services and had her first child. After leaving GMTV, she made several guest appearances on Loose Women in 2005. During Kaye Adams' pregnancy in 2006, Brambles hosted the show in Adams' place, which led to her becoming the new leading host of the show. On 7 August 2009, she closed her final show.
Brambles owns her own digital media business called Broadstance Digital Media Production.
In June 2009, Brambles was a commentator on the political show This Week; her topic was girl power. Throughout 2009-2010, Brambles was also guest presenter of various shows on BBC Radio Scotland. From September 2010 and Summer 2012 she has been a regular guest presenter of the ITV Breakfast programme Lorraine.
Brambles married second husband David Todd (born 23 March 1975) on 5 August 2005. The couple has two children as a result of which Brambles left GMTV to concentrate on motherhood. In December 2008,Nuts magazine held their annual 'Woman I Secretly Adore' poll, in which Brambles came second with 18% of the vote. She was beaten by GMTV presenter Kate Garraway, who received 21%.