The character, played by the Cold Feet actress Fay Ripley, makes her debut in television ads breaking nationally this week.
The initiative is part of a £12 million investment by Camelot in marketing activity between now and the end of the year.
Created by Abbott Mead Vickers BBDO, Lady Luck takes an unashamedly positive outlook on life, dispensing advice in a self-assured and mischievous way, while urging people to "think lucky".
The voiceover for her companion, Barry, a miniature pet unicorn, is provided by the comedian and chat-show host Graham Norton.
Ripley, who replaces Billy Connolly as the face of Lotto, stepped into the part after the US film actress Whoopi Goldberg is said to have turned down the role because of her fear of flying to the UK.
The advertising is intended to build on what Camelot claims has been the National Lottery's longest period of sales growth for seven years, with ticket sales between April and June showing a 5.7 increase over the corresponding period last year.
The Lady Luck creative work will feature across all of Camelot's marketing activity including TV, radio, online, direct marketing and point-of-sale.
Media planning is being handled by Media Planning Group and buying by OMD UK.
Lady Luck makes her opening appearance in two 30-second spots. In the first, set in a newsagent, she points out to a man staring enviously at a picture of a Lamborghini in a magazine that his chances of owning such a car might improve if he bought a lottery ticket.
In the second, she chides her unicorn for the time he's taking to get ready. "Are you coming or shall I get myself a lucky rabbit?" she asks.
The ads were written by Derek Apps and art directed by Tom Notman. They were directed by David Kellogg through Academy.