Ham was born in Queensland, Australia, but moved to the United States of America in 1987. He has a bachelor's degree in applied science (with an emphasis on environmental biology) from the Queensland Institute of Technology and also holds a Diploma of Education from the University of Queensland.On December 30, 1972, he married Marilyn ("Mally"), whom he describes as a "very, very submissive, supportive wife" who has "always supported me five million percent". The couple have five children...two are married and two live with them in the Cincinnati area...and have five grandchildren.

In 1979, Ham co-founded what was to be later known as the Creation Science Foundation (CSF) in Queensland, Australia with John Mackay. .

Between 1987 and 1993, Ham worked for the Institute for Creation Research (ICR), one of the oldest American Creationist organisations, and a leading young-Earth organisation. In 1994, with the assistance of what is now Creation Ministries International (Australia), Ham and colleagues Mark Looy and Mike Zovath set up Creation Science Ministries, later renamed Answers in Genesis. The Christian ministry specialises in Young Earth Creationism, and is primarily devoted to convincing people that the initial chapters in Genesis should be taken as literally true and historically accurate. For his contributions to evangelism, he has been granted two honorary degrees (by Temple Baptist College in 1997 and by Liberty University in 2004). Answers in Genesis opened its $27 million, Creation Museum in Petersburg, Kentucky, on May 28, 2007.

Also in May 2007, Creation Ministries International (CMI) filed a lawsuit against Ham and AiG in the Supreme Court of Queensland seeking damages and accusing him of deceptive conduct in his dealings with the Australian organization. Members of the ministry were "concern[ed] over Mr Ham's domination of the ministries, the amount of money being spent on his fellow executives and a shift away from delivering the creationist message to raising donations." According to the CMI website, this dispute was amicably settled in April 2009.

In 2008, Ham appeared in Bill Maher's comedy Religulous. In a press release AiG criticized the movie for what it called Maher's "dishonesty last year in gaining access to the Creation Museum and AiG President Ken Ham."

Ham hosts Answers. . . with Ken Ham, an internet and radio program broadcasting daily on over nine hundred radio stations worldwide and featuring Ham's commentary on issues.

As a young Earth creationist, Ham believes that the entire universe was created about 6,000 years ago and that Noah's flood occurred about 4,500 years ago. He believes that this explains how a small number of animals carried on Noah's ark could produce the biological diversity observed on Earth. Ham also believes that dinosaurs co-existed with modern humans. He supports this claim with both scripture and with the same evidence that secular scientists use. He once said to a Christian audience regarding his opposition to racism, "If you disagree with what I'm going to say, please do not give me your opinion, because I'm not interested...I want to know what the Bible says."

Ham accepts that natural selection can give rise to a number of species from an original population, by Mendelian recombination of already existing genes. He believes that new genes cannot arise from mutations, because this would be "adding information" (he claims that only intelligence can cause a beneficial mutation); instead, mutations and natural selection can only "remove preexisting information." Furthermore, all of these species are of the same kind and no new kind can arise from this process.

Since 1989, Ham has frequently made the comment, "Were you there?" regarding the origins of life and evolution, implying that knowledge of unwitnessed events is inferential and not observational. Talk.origins responded that the evidence for evolution "was there." In 2005, The Daily Show poked fun at Ham's question.

Ham's beliefs and tactics have also been criticized by other Christians and Old earth creationists. Answers in Creation, an Old Earth creationist web site, has called Ham willfully ignorant of evidence for an old earth and said that he "deliberately misleads" his audiences on matters of both science and theology. Astronomer Hugh Ross, a progressive creationist, has publicly debated Ham on the age of the Earth and the compatibility of an old Earth with the Bible, as well as other Answers In Genesis staff.