The Born Free star took time away from her charity work to begin the new chapter of Ellesmere Library after it moved from its home in Fullwood House to become part of a new community facility in the nearby Meres Day Centre.
The new facility will managed by the Shrewsbury-based social care charity Bethphage, which is taking over the operation of the day centre and the library from Shropshire Council.
Ms McKenna said: "This is a good news day. The determination to keep Ellesmere Library alive was unshakable.
"I'm sure this library is certain of a lasting future because of the firm commitment of the groups and the fantastic opportunity this is for people of all ages to hold a book in their hands, turn the pages and get lost in a story. If they get half the satisfaction as I did all those years ago, they will be rich indeed.
"I'm absolutely passionate about books. As a child I'd bury myself in a chair with a book, oblivious to the world around me, but these days children are buried in laptops and that's a whole different world.
"I still have books from my childhood, including Baba the Elephant – maybe that was a hint at things to come.
"If I lived in Ellesmere I know I'd be in and out of this library every single week, and I hope it will be a centre of interest, enjoyment, intellectual adventure and discovery for all ages and all tastes.
As well as officially opening the library, Ms McKenna has donated two of each of her books. She also met the winners of a children's art competition, based on a wildlife theme.
The proposal to relocate the library and customer service point was put forward by the council two years ago as one of the cost-saving options in a programme of major spending cuts in public services Local people, concerned about the potential loss of such a much-loved facility, held a public meeting in September 2015 and the Friends of Ellesmere Library was formed to try to safeguard its future.
With almost 200 members, the Friends’ mission is to ensure that there is no downgrading of the services currently provided. They are also firmly committed to enhancing and supporting the library and raising its public profile through a wide range of activities and events for children and adults.