Solomon writes that he was an adviser to President Jimmy Carter's task force on the environment in the late 1970s, which released The Global 2000 Report to the President in 1980. He has a regular column in The National Post, and has written for The Globe and Mail, National Review Online, CBS News, and The Wall Street Journal. He was the editor and publisher of Next City magazine, now defunct. He has also written for American Forests, an environmental conservation organization.

Serving as executive director of the Urban Renaissance Institute, a division of Energy Probe, Solomon has advocated environmental protection, conservation, and safeguards throughout the world, especially in non-affluent nations. He supports reforms in foreign aid, putting a stop to nuclear power expansion, and supports the privatization of transport projects and the expansion of toll roads. "I note that Lawrence Solomon continues to advocate road tolls, and the privatization of the TTC (like London) for Toronto's transportation system." Bruce Campion-Smith In his columns and his book Toronto Sprawls: A History, he blames government policy for exacerbating and encouraging sprawl. He is a critic of subsidies to rural Canada, and has criticized Ontario Hydro's actions and projects and their effects on Canada's environment. He writes that he was very active during the 1970s and 1980s with Energy Probe in opposing attempts to expand the use of nuclear power in Canada.

In a series of articles and a companion book published in 2008, The Deniers, Solomon writes about scientists whose views and research, according to Solomon, contradicts what he calls the alarmist view of global warming presented by Al Gore, the IPCC and the media. The book featured on C-SPAN's Book TV on May 11, 2008. Reviews of the book have appeared in the Washington Times, Vancouver Sun, Alternatives Journal, and other publications.

In December, 2008, an executive from the U.S. Chamber of Commerce's Institute for 21st Century Energy sponsored a debate about global warming between Lawrence Solomon and Dr. Jay Gulledge of the Pew Center on Global Climate Change, who took the opposite view. Solomon's blog has been mentioned in U.S. News & World Report's website concerning carbon emissions reduction legislation.

According to Elaine Kurtenbach for America's Intelligence Wire, Solomon discovered and revealed that the IPCC used a flawed and non-peer reviewed paper by James Hansen and Eigil Friis-Christensen as support for the IPCC's conclusions on the correlation between land based global temperatures that had been contaminated by proximity to expanding urban areas with rising atmospheric CO2.

Solomon has also written columns criticizing Wikipedia's coverage of global warming and other topics, including his own Wikipedia biography page.

In 2004, Solomon founded Green Beanery, a non-profit online merchant specializing in organic coffee beans produced by small, independent farmers. The company is located in downtown Toronto and includes a cafe where customers can sample a wide variety of coffee. The profits from Green Beanery go to Probe International.

Solomon's books include:

• The Conserver Solution (Doubleday, 1978 ISBN 978-0385145336)
• Energy shock: After the oil runs out (Doubleday, 1980 ISBN 978-0385171618)
• Breaking up Ontario Hydro's Monopoly (Energy Probe, 1982)
• Power at What Cost (Doubleday, 1984 ISBN 978-0919849037)
• In the Name of Progress (with Patricia Adams) (Earthscan, 1992 ISBN 978-1853831218)
• Toronto Sprawls: A History (University of Toronto Press, 2007 ISBN 978-0772786180)
• The world-renowned scientists who stood up against global warming hysteria, political persecution, and fraud (Richard Vigilante Books, 2008 ISBN 978-0980076318)