Born in Damascus, Syria, when he was seven his family emigrated to Seattle (USA).
He is married to Yvette Nagel, daughter of former Leefbaar Nederland political party president and politician Jan Nagel.
For many years he the chief-editor of the Inside Chess Magazine, which however later became an Internet-only magazine and later just a Column at the Chesscafe website.
In the year 2001 (?), Seirawan released a plan to reunite the chess world, which at that time had two world champions: Ruslan Ponomariov had gained the title under the auspices of FIDE, while Vladimir Kramnik had beaten Gary Kasparov to take the Einstein title. It called for one match between Ponomariov and Kasparov (the world number one), and another between Kramnik and the winner of the 2002 Einstein tournament in Dortmund (who turned out to be Peter Leko). The winners of these matches would then play each other to become undisputed World Champion. This plan was signed by all parties on May 6, 2002, in the so called "Prague Agreement". As of October 2003, neither of these matches have taken place, and it is unclear whether they ever will.
There have been reports that the series of events Seirawan participated in in China during September 2003 will be his last as a professional player.