The 63-year-old Irish actor recalled his wedding to the English actress on the My Favorite Song radio show with John Benjamin Hickey. Neeson revealed Richardson serenaded him with Van Morrison song "Crazy Love" at their 1994 wedding in Northern Ireland.
"It's a romantic ballad," the star explained. "Behind my back, Natasha had been taking singing lessons to sing it to me. After the ceremony, we were all going in to start the night's festivities and she grabbed the microphone and sang me this ... I was like, 'Wow.'"
Neeson and Richardson had been married nearly 15 years when the actress died of injuries from a skiing accident in March 2009. The actor opened up about Richardson in a 60 Minutes interview in 2014, telling Anderson Cooper his wife's death "never" seemed real.
"[Sometimes] I still think I'm going to hear her," he said. "[Grief is] like a wave. You just get this profound feeling of instability... the Earth isn't stable anymore, and then it passes and it becomes more infrequent, but I still get it sometimes."
Richardson is also survived by the couple's two sons, 20-year-old Michael and 19-year-old Daniel, the elder of whom has pursued acting. Michael admitted to abusing alcohol and drugs after his mom's death in an interview with The Sunday Times in March.
Neeson will star in a number of forthcoming films, including a Martin Scorsese adaptation of the Shusaku Endo novel Silence. The actor is also slated for A Monster Calls with Sigourney Weaver and Felt with Diane Lane.