The borough received its franchisement in 1547 to return two members of parliament. It is believed that parliamentary representation was secured by the Bishop of Exeter who was Lord of the Manor. All the male inhabitants who paid rates (Scot and Lot) were entitled to vote. In 1716 they totalled about 120 around one third of the adult male population. By 1830, the number was approximately 400. The principle influence of voters was bribery around economic pressures of landowners. There was no secret ballot at this time. Many members of parliament were non-entities who rarely set foot in Penryn. In most boroughs, the hold of the local gentry was so strong that a contest was hardly necessary. In Penryn, elections were controlled by Lord Edgecumbe and Lord Falmouth. When an outside candidate made a challenge, the returning officer could manipulate the voting figures. There was multiple Parliamentary inquiries into how Penryn conducted its elections. The borough elections have a history of open bribery and corruption. In 1818, a Bill was introduced in the House of Commons for preventing the bribery and corruption for the election of members in Penryn. Followed by a similiar Bill in 1826 and 1828.
In 1832, Penryn was united with Falmouth. The union of Penryn and Falmouth returned two members until 1885 when it was reduced to one member. In 1918, it ceased to exist as a Parliamentary borough and the consituency was known as the Penryn / Falmouth division.
The borough council was not directly chosen by the people they represented. It was a self perpetuating oligarchy. An initial list was drawn up at the time of charter of 1621. Vacancies were filled by decisions of the remaining members of the Council. By the Municipal Corporations Act of 1835, the borough council was elected by the adult ratepayers of three years standing. The borough obtained its income through the properties it owned, market fees, and harbour fees.