The son of Sir Walter fitz Gilbert of Cadzow de Hameldone, he succeeded his father as Baron of Cadzow before 1346, when he was captured at the Battle of Neville's Cross.
He was considered an important enough captive to be held by William Zouche, Archbishop of York, under special terms that he not be released, except under command of Edward III of England.
The next reference to David fitz Walter is in 1361 when he endowed Glasgow Cathedral with a Chaplainry.
David fitz Walter took part in the sittings of the Parliament of Scotland in 1371 and 1373, the latter to confirm John Stewart, Earl of Carrick and his successors as heirs to the throne of Scotland.
The charter, at New Register House in Edinburgh, still has his seal appended, with the three cinquefoils for Hamilton, and the inscription,: Sigill David filii Walter.