Whitelocke stood, on the whole, well with Francis Bacon, to whom he owed his investiture as serjeant-at-law on 29 June 1620 and subsequent advancement on 29 October. He was given in 1620 the then important position of chief justice of the court of session of the County Palatine of Chester and the great sessions of the counties of Montgomery, Denbigh, and Flint. He was knighted on 4 October 1620. Shortly afterwards he was elected recorder by each of the four boroughs of Bewdley in Worcestershire, Ludlow and Bishop's Castle in Shropshire, and Poole, Cheshire. Differences with the president of the council in the Welsh marches (the Earl of Northampton) led to Whitelocke's transfer from the Chester court to the king's bench, where he was sworn in as justice on 18 October 1624. He had also a commission to hear causes in chancery, and sat once in the star-chamber. He was re-elected MP for Woodstock in 1621.