The Atlantic 85 was funded by a bequest from Ann Constance Setten, from Shropshire, before her death.
It has been named Ann and Peter Setten after her and her husband at a ceremony at Abersoch RNLI by her niece Liz Badman and great-niece Sarah Flook.
The lifeboat was given the seal of approval by the Duke of Kent Prince Edward, the Queen's cousin and president of the RNLI.
Ms Badman said: "My aunt always loved anything to do with boats, the sea and the Navy and she also had an interest in the lifeboats from her childhood holidays."
The lifeboat, which replaces the station's outgoing Atlantic 75 lifeboat, is able to carry a fourth crew member and has improved space for kit.
A new RNLI lifeboat has been named during a ceremony in Gwynedd.