Willis tends to the comedy of manners style of writing. Her protagonists are typically beset by single-minded people pursuing illogical agendas, such as attempting to organize a bell-ringing session in the middle of a deadly epidemic (Doomsday Book), or frustrating efforts to analyze Near-death experiences by putting words in the mouths of interviewees (Passage).

Other themes and stylistic devices include:

• a scientist as protagonist (the main theme of Bellwether, but also present in Uncharted Territory, Passage, and...to a lesser degree...the Fire Watch universe stories)
• an aversion to rampant political correctness (notably the over-appreciation of indigenous cultures in Uncharted Territory, anti-smoking stances in Bellwether, censorship of "addictive substances" in Remake and censorship of an English class in the short story "Ado")
• the inclusion of meticulously researched, detailed trivia related tangentially or symbolically to the narrative (fads in Bellwether, mating customs in Uncharted Territory, old movies in Remake, the Titanic disaster in Passage, famous pairs of ill-fated lovers in To Say Nothing of the Dog)
• the constant presence of trying to come to terms with grief, loss, and death; this is often attributed to her mother having died while Willis herself was still a child.

Willis is acclaimed as a science-fiction writer, with much of her writing exploring the social sciences. She often weaves technology into her stories in order to prompt readers to question what impact it has on the world. For instance, Lincoln's Dreams plumbs not just the psychology of dreams, but also their role as indicators of disease. The story portrays a young man's unrequited love for a young woman who might or might not be experiencing reincarnation or precognition, and whose outlook verges on suicidal. Similarly Bellwether is almost exclusively concerned with human psychology.

Among other themes, Uncharted Territory contemplates the extent to which technology shapes expectations of gender; "technology" here ranges from a land rover and binoculars to Built's online "tchopping" and the pop-up holograms...even socioexozoology. Remake embraces old movies and the computer graphics revolution, as well as intellectual property, digital copyright issues, and the question of public domain.

Other Willis stories explore the so-called "hard" sciences, following in the classic science fiction tradition. "The Sidon in the Mirror" harks back to the interplanetary and interstellar romanticism of the 1930s and 1940s. "Samaritan" is another take on the theme of Heinlein's "Jerry Was a Man", while "Blued Moon" is similarly reminiscent of Heinlein's "The Year of the Jackpot".

Hugo Awards

Wins

• Fire Watch : novelette : 1983
• The Last of the Winnebagos : novella : 1989
• Doomsday Book : novel : 1993
• Even the Queen : short story : 1993
• Death on the Nile : short story : 1994
• The Soul Selects Her Own Society: Invasion and Repulsion: A Chronological Reinterpretation of Two of Emily Dickinson's Poems: A Wellsian Perspective : short story : 1997
• To Say Nothing of the Dog : novel : 1999
• The Winds of Marble Arch : novella : 2000
• Inside Job : novella : 2006
• All Seated on the Ground : novella : 2008

Additional Nominations

• Daisy, In the Sun : short story : 1980
• The Sidon in the Mirror : novelette : 1984
• Blued Moon : novelette : 1985
• Spice Pogrom : novella : 1987
• At the Rialto : novelette : 1990
• Time-Out : novella : 1990
• Cibola : short story : 1991
• In the Late Cretaceous : short story : 1992
• Jack : novella : 1992
• Miracle : novelette : 1992
• Remake : novel : 1996
• Passage : novel : 2002
• Just Like the Ones We Used to Know : novella : 2004

Nebula Awards

Wins

• Fire Watch : novelette : 1983
• A Letter from the Clearys : short story : 1983
• The Last of the Winnebagos : novella : 1988
• At the Rialto : novelette : 1990
• Doomsday Book : novel : 1993
• Even the Queen : short story : 1993

Additional Nominations

• The Sidon in the Mirror : novelette : 1984
• Schwarzschild Radius : novelette : 1988
• Jack : novella : 1992
• Death on the Nile : novelette : 1994
• Bellwether : novel : 1998
• To Say Nothing of the Dog : novel : 1999
• Passage : novel : 2002
• Just Like the Ones We Used to Know : novella : 2005

Locus Awards

Wins

• Doomsday Book: SF novel: 1993
• To Say Nothing of the Dog: SF Novel: 1999
• Passage: SF novel: 2001

Additional Nomination

• Lincoln's Dreams: Fantasy Novel: 1988

Arthur C. Clarke Awards

Nominations

• Doomsday Book: SF novel: 1993
• Passage: SF novel: 2001

World Fantasy Awards

Nominations

• Chance : novella : 1987
• The Winds of Marble Arch : novella : 2000

John W. Campbell Memorial Award

Win

• Lincoln's Dreams: 1988

British Science Fiction Association Awards

Nomination

• Doomsday Book: SF novel: 1993

Novels and published-seperately novellas

• Water Witch (1982) (with Cynthia Felice)
• Lincoln's Dreams (1987) - John W. Campbell Memorial Award winner, Locus Fantasy Award nominee, 1988
• Light Raid (1989) (with Cynthia Felice)
• Doomsday Book (1992) - Nebula Award winner, BSFA Award nominee, 1992; Hugo and Locus SF Awards winner, Clarke Award nominee, 1993
• Remake (1994) - Hugo Award nominee, 1996
• Uncharted Territory (1994)
• Bellwether (1996) - Nebula Award nominee, 1997
• Promised Land (novel) (1997) (with Cynthia Felice)
• To Say Nothing of the Dog (1998) - Hugo and Locus SF Awards winner, 1999; Nebula Award nominee, 1998
• Passage (2001) - Locus SF Award winner, Hugo and Clarke Awards nominee, 2002; Nebula Award nominee, 2001
• Inside Job (2005)
• D.A. (2007)
• "All Seated on the Ground" (2007)
• Blackout (2010)
• All Clear (announced for a fall 2010 publication)

Short story collections

• Fire Watch (1984), whose title story won the 1982 Hugo and Nebula Awards
• Impossible Things (1993)
• Futures Imperfect (1996) (omnibus edition of Uncharted Territory, Remake and Bellwether.)
• Even the Queen: And Other Short Stories (1998) - Sound recording of five stories read by Connie Willis including "Even the Queen", "Death on the Nile", and "At the Rialto".
• Miracle and Other Christmas Stories (1999)
• A Connie Willis Compendium (2007)

Short stories

• "Samaritan" (1978) - Collected in Fire Watch and A Connie Willis Compendium
• "Capra Corn" (1978) - Collected in the "Limited/Lettered Editions" of A Connie Willis Compendium
• "Daisy, in the Sun" (1979) - Collected in Fire Watch
• "And Come from Miles Around" (1979) - Collected in Fire Watch
• "The Child Who Cries for the Moon" (1981) - Collected in A Spadeful of Spacetime
• "Distress Call" (1981) - Published separately by Roadkill Press and collected in two anthologies
• "A Letter from the Clearys" (1982) - Collected in Fire Watch and A Connie Willis Compendium
• "Fire Watch" (1982) - Collected in Fire Watch and A Connie Willis Compendium
• "Service For the Burial of the Dead" (1982) - Collected in Fire Watch and A Connie Willis Compendium
• "Lost and Found" (1982) - Collected in Fire Watch
• "The Father of the Bride" (1982) - Collected in Fire Watch
• "Mail Order Clone" (1982) - Collected in Fire Watch
• "And Also Much Cattle" (1982)
• "The Sidon in the Mirror" (1983) - Collected in Fire Watch
• "A Little Moonshine" (1983)
• "Blued Moon" (1984) - Collected in Fire Watch and A Connie Willis Compendium
• "Cash Crop" (1984) - Collected in A Connie Willis Compendium
• "Substitution Trick" (1985) - Collected in the "Limited/Lettered Editions" of A Connie Willis Compendium
• "The Curse of Kings" (1985) - Collected in A Connie Willis Compendium
• "All My Darling Daughters" (1985) - Collected in Fire Watch and A Connie Willis Compendium
• "And Who Would Pity a Swan?" (1985)
• "With Friends Like These" (1985)
• "Chance" (1986) - Collected in Impossible Things and A Connie Willis Compendium
• "Spice Pogrom" (1986) - Collected in Impossible Things
• "The Pony" (1986) - Collected in Miracle and Other Christmas Stories
• "Winter's Tale" (1987) - Collected in Impossible Things
• "Schwarzchild Radius" (1987) - Collected in Impossible Things
• "Circus Story" (1987)
• "Lord of Hosts" (1987)
• "Ado" (1988) - Collected in Impossible Things and A Connie Willis Compendium
• "The Last of the Winnebagos" (1988) - Collected in Impossible Things and A Connie Willis Compendium
• "Dilemma" (1989)
• "Time Out" (1989) - Collected in Impossible Things
• "At the Rialto" (1989) - Collected in Impossible Things, A Connie Willis Compendium and "Even the Queen: And Other Short Stories" (1998) recoding
• "Cibola" (1990)
• "Miracle" (1991) - Collected in Miracle and Other Christmas Stories
• "Jack" (1991) - Collected in Impossible Things and A Connie Willis Compendium
• "In the Late Cretaceous" (1991) - Collected in Impossible Things and A Connie Willis Compendium
• "Much Ado About [Censored]" (1991)
• "Even the Queen" (1992) - Collected in Impossible Things, A Connie Willis Compendium and "Even the Queen: And Other Short Stories" (1998) recoding
• "Inn" (1993) - Collected in Miracle and Other Christmas Stories and A Connie Willis Compendium
• "Close Encounter" (1993)
• "Death on the Nile" (1993) - Collected in "Even the Queen: And Other Short Stories" (1998) recoding
• "A New Theory Explaining the Unpredictability of Forecasting the Weather" (1993)
• "Why the World Didn't End Last Tuesday" (1994)
• "Adaptation" (1994) - Collected in Miracle and Other Christmas Stories
• "The Soul Selects Her Own Society: Invasion and Repulsion: A Chronological Reinterpretation of Two of Emily Dickinson's Poems: A Wellsian Perspective" (1996) - Collected in A Connie Willis Compendium
• "In Coppelius's Toyshop" (1996) - Collected in Miracle and Other Christmas Stories
• "Nonstop to Portales" (1996) - Collected in A Connie Willis Compendium
• "Newsletter" (1997) - Collected in Miracle and Other Christmas Stories and A Connie Willis Compendium
• "Epiphany" (1999) - Collected in Miracle and Other Christmas Stories and A Connie Willis Compendium
• "deck.halls@boughs/holly" (2001)
• "Just Like the Ones We Used to Know" (2003) - Collected in A Connie Willis Compendium
• "New Hat" (2008)
• "The Winds of Marble Arch" - Collected in A Connie Willis Compendium
• Cat's paw - Collected in Miracle and Other Christmas Stories

Other

• Roswell, Vegas, and Area 51: Travels with Courtney (2002)

Essays

• On Ghost Stories (1991)
• Foreword (1998)
• Introduction (1999)
• The Nebula Award for Best Novel (1999)
• The 1997 Author Emeritus: Nelson Bond (1999)
• The Grand Master Award: Poul Anderson (1999)
• A Few Last Words to Put It All in Perspective (1999)
• Bibliography, including a list of all of her SF short stories and "confessions" stories, collected in the "Limited/Lettered Editions" of A Connie Willis Compendium
• A Final Word; Twelve Terrific Things to Read... (Christmas stories); And Twelve to Watch (Christmas movies); all collected in Miracle and Other Christmas Stories