He was commissioned lieutenant on 26 February 1757 and promoted commander on 1 July 1766, joining the Swift 14 and taking her on a special mission to the Falklands in September 1767. She left the islands in early February 1769 and reached home in May to be paid off.
Raynor was posted captain on 26 July 1775 and recommissioned the Chatham 50 as flagship of Rear-Admiral Molyneux Shuldham, sailing in October for North America and retaining her until exchanging with Captain Tobias Caulfield into the Bristol 50 in September 1776. In the course of this period he superintended the landing of the Army on Staten Island during the New York campaign of July – October 1776.
He had the Bristol 50, going out to New York with a convoy in September 1777 and then joined the fleet in the Delaware before sailing north to Rhode Island. When Rear-Admiral Parker was despatched to command the Jamaica station at the end of the year he took the Bristol as his flagship. Raynor was replaced by Captain Tobias Caulfield in the early part of 1778 and commanded the Isis 50 in Vice-Admiral Lord Howe’s fleet in the defence of New York during July 1778 and manoeuvres off Rhode Island in August 1778. Following the latter action his ship was chased and engaged by the César 74 before the latter withdrew, having had her wheel shot away and with the French captain losing his arm. One contemporary commentator claimed that this action was as memorable as any in the Navy’s history hitherto.
The Isis later joined Commodore William Hotham’s reinforcements for the Leeward Islands, which sailed from New York in November. He took part in the Battle of St. Lucia on 15 December 1778 , and having returned to England earlier in the summer with the trade he commanded the Isis during the Channel fleet retreat of August 1779.
In February 1780 Captain Raynor commissioned the new Inflexible 64 but he died at sea on 25 August 1780.