The focus of Vassanji's work is the situation of East African Indians. As a secondary theme, members of this community (like himself) later undergo a second migration to Europe, Canada, or the United States. Vassanji examines how the lives of his characters are affected by these migrations: "[the Indian diaspora] is very important...once I went to the US, suddenly the Indian connection became very important: the sense of origins, trying to understand the roots of India that we had inside us" (Kanaganayakam, p. 21). Vassanji looks at the relations between the Indian community, the native Africans and the colonial administration. Though few of his characters ever return to India, the country's presence looms throughout his work; his 2007 novel The Assassins Song, however, is set almost entirely in India, where it was received as an Indian novel.

Vassanji is concerned with the effects of history and the interaction between personal and public histories. The colonial history of Kenya and Tanzania serves as the backdrop for his work, but it is the personal histories of the main characters that drive the narrative. Vassanji's presentation of the past is never cut-and-dried. He avoids the impression of, a simple, linear, historical truth emerging. In much of his work the mysteries of the past remain unresolved. (Kanaganayakam p. 22). He consistently refuses to be pigeonholed by nationality or faith, attempts to do which he finds offensive and malicious.

Vassanji's work has received considerable critical acclaim. The Gunny Sack won a regional Commonwealth Writers Prize in 1990. In 1994, he won the Harbourfront Festival Prize in recognition of his "achievement in and contribution to the world of letters." That year he was also one of twelve Canadians chosen for Maclean's Magazine's Honour Roll. Vassanji won the inaugural Giller Prize in 1994 for The Book of Secrets. He again won the Giller Prize in 2003 for The In-Between World of Vikram Lall. He was the first writer to win the Giller Prize more than once. (In 2004, Alice Munro became the prize's second repeat winner.) In 2006, When She Was Queen was shortlisted for the City of Toronto Book Award.

His latest work, The Assassin's Song was short-listed for the 2007 Giller Prize.

In 2005, he was made a Member of the Order of Canada.

Novels

• The Gunny Sack (1989) ISBN 0-38566-065-0
• No New Land (1991) ISBN 0-77108-722-5
• The Book of Secrets (1994) ISBN 0-31215-068-7
• Amriika (1999) ISBN 0-77108-725-X
• The In-Between World of Vikram Lall (2003) ISBN 0-38565-991-1
• The Assassin's Song (2007) ISBN 0-38566-351-X

Short story collections

• Uhuru Street (1992)
• When She Was Queen (2005)

Non-fiction collections

• A Place Within (2008)