Ms Keal, who lives in Norton, will be looking to displace Conservative Kevin Hollinrake as the constituency’s MP.
The seat is also being contested by Labour’s Alan Avery.
Ms Keal has served as a councillor on the town council since 2000 and as a district member from 2005.
She is married to Howard and they have three daughters, Hannah, Molly and Emily.
Ms Keal stood in the 2015 General Election and said she was looking forward to campaigning again in 2017.
“Many local people feel let down by the current MP who has betrayed them in his support for the shale gas industry which threatens tourism, agriculture and our beautiful countryside.
“Voters are also deeply concerned about the Tories tearing the heart out of the NHS and their plan for devastating budget cuts to our local schools, threatening reduced teacher numbers and resulting in bigger class sizes.
“Thousands of people living on basic pensions across the constituency are facing a bleak future with the Tories ripping up the protection provided by the triple lock on pensions, which was introduced by the Liberal Democrats.
“Theresa May’s rush towards a hard Brexit can only make things worse for the local economy in terms job losses and the end of agricultural subsidies for farmers when we leave the EU.
“The Liberal Democrats are the only political party willing to stand up the Tories and challenge the damage that they are doing to the country and right here in Thirsk and Malton.”
The Lib Dem candidate said her recent campaigns had included lobbying for better flood protection across the area including for Norton and Malton and spearheading the campaign that led to the building of the £10.3m flood defences that currently protect Malton, Norton and Old Malton.
Di, with Howard, fought for the creation of the Malton Sports Centre, is chair of a local social history project, The Woodhams-Stone Collection, established the Castle Garden in Malton and is a founder member of Action on Traffic, a residents group set up to tackle congestion and air-pollution.