Elvis won the national category for its Compassion in World Farming ad while 438 Marketing's creative work for Williams Group, Mini took the top spot in the regional category.
National bus advertising space worth £200,000 for Elvis and regional bus advertising worth £25,000 for 438 Marketing was awarded and the creative teams behind the campaigns were rewarded with £2,000 of department store vouchers.
The winners were chosen by a panel of judges from over 600 entries and announced at The London Transport Museum last night, where guests were able to view a creative showcase of submitted work.
Will Awdry, creative partner at Ogilvy & Mather, an award judge, commended Elvis' ad for "using the medium to make the point about other means of transport" and Claire Beale, editor of Campaign, also an award judge, said it was "a worthy winner".
438 Marketing was praised by award judge Margaret Jobling, marketing director of Birds Eye UK. "It says something surprising about a Mini in an execution that is relevant to the medium," she said.
Four other finalists were shortlisted in the national category; McCann Erickson London for B&Q; Iris, the winner of last year's CBS Long Copy Challenge, for Butlins; BJL for Crown Paints and Leo Burnett for McDonald's Drive Thru.
In the regional category 438 Marketing was up against Publicis Life Brands Resolute for Allergan Ophthalmology, Optive; Family Advertising for Crimestoppers, Knife Crime; and Hunterlodge Advertising for London Fire Brigade.
Abott Mead Vickers BBDO was also commended for its regional entry for Sainsbury's Alperton.
The judging panel of leading industry figures included Nick Ashley, head of client leadership at Mindshare; Alan Brydon, head of trading at MPG Media Contacts; Murray Calder, director of MediaCom, Edinburgh; Damon Collins, executive creative director of RKCR/Y&R; Jason Cotterrell, country director of CBS Outdoor, UK; Simon Dicketts, worldwide executive creative director of M&C Saatchi; Simon Harrington, marketing director of CBS Outdoor, UK; and Mark Yexley, commercial and operations director of Arriva UK Bus.
The winning and shortlisted entries can be viewed in an online gallery at www.bigbuschallenge.com.