In 1070, Judith married Earl Waltheof of Huntingdon and Northumbria. They had three children. Their eldest daughter, Maud, brought the earldom of Huntingdon to her second husband, David I of Scotland. Their daughter, Adelise, married Raoul III de Conches whose sister, Godehilde, married Baldwin I of Jerusalem.
In 1075, Waltheof joined the Revolt of the Earls against William. It was the last serious act of resistance against the Norman conquest of England. Judith betrayed Waltheof to her uncle, who had Waltheof beheaded on 31 May 1076.
After Waltheof's execution Judith was betrothed by William to Simon I of St. Liz, 1st Earl of Northampton. Judith refused to marry Simon and she fled the country to avoid William's anger. William then temporarily confiscated all of Judith's English estates. Finally, Simon married Judith's daughter, Maud, in or before 1090.
The parish of Sawtry Judith in Huntingdonshire is named after the Countess.
In POTONE Hugh holds ½ virgate of land from the Countess. Land for 1 plough; it is there, with 1 smallholder. The value is and was 5s; before 1066, 2s. Earl Tosti held this land in Potton, his manor.