Mullan continued developing his directing style with two more shorts, "Good Day for Bad Guys" (1995) and the award-winning Tartan film "Fridge" (1996), the latter a brutal but finely observed human drama in which two alcoholics struggle to free a young boy trapped in a disused freezer. His mother's 1994 death provided the impetus for his feature directorial debut, "Orphans" (1998), a movie which followed four working-class siblings around the bleak Glasgow streets for the 24 hours prior to their mother's funeral. Described in The New York Times as the most misanthropic film the critic had ever seen, Mullan's imaginative world is arbitrary and unpredictable, poised with an awful openness between hope and despair. At times moving, surreal and hilarious, "Orphans" climaxes in a wonderful scene in which the dutiful eldest son insists on carrying the coffin to the grave on his back, proclaiming: "She ain't heavy, she's my mother." The director assembled the same creative team (producer, cinematographer, editor) that previously had worked with him on "Close" and "Fridge".
Mullan broke off from editing "Orphans" to appear in Loach's "My Name Is Joe" (also 1998), setting the stage for that year's Cannes Festival showcase of both pictures which thrust the actor-director from obscurity into the light of international recognition. As the title character, Mullan gave a subtle, layered and nuanced portrayal of a recovering Glasgow alcoholic, free from the trappings of the stage drunk, a depiction of a man trying to keep his problem under control. If his mother inspired "Orphans", certainly his father served as the model for the "self-pitying, aggressive, bitter drunk" that emerges when the engaging, sympathetic character falters and drinks again. Appearing often throughout the film in searching close-up, Mullan delivered a naturalistic performance, described by one critic as "all the more impressive because you never actually catch him acting," and picked up the Best Actor honors at Cannes. He followed with roles in "Ordinary Decent Criminal", a fictionalized version of the life of Irish criminal Martin Cahill opposite Kevin Spacey and Linda Fiorentino, and as Jean opposite Saffron Burrows' "Miss Julie" (both 1999), in Mike Figgis' film adaptation of the Strindberg play. The following year, he offered a fine turn as a gold prospector who sells his wife and daughter for a chance to earn a fortune in "The Claim", a version of the Thomas Hardy novel "The Mayor of Castorbridge" set in 1860s California.