The British funnyman tied the knot with the "Roar" hitmaker in a traditional Hindu ceremony in India in 2010 after dating for just over a year.
However, the relationship soon fell apart and, in late 2011, Russell announced the couple was divorcing.
Although the union ultimately failed, the "Forgetting Sarah Marshall" star wants nothing but the best for his ex-wife, who has since found love with fiance Orlando Bloom, the father of her baby daughter Daisy.
Answering questions on TikTok as part of a week-long series of #LearnOnTikTok LIVEs, he said, "I really tried in that relationship. I have nothing but positive feelings for her."
Katy previously revealed their conflicting career schedules and her hesitation to start a family at that time contributed to the end of their marriage.
Russell went on to wed Laura Gallacher in 2017 and the couple shares daughters Mabel, five, and two-year-old Peggy.
Last year in a magazine interview, Katy Perry claimed she fell into dark place following her divorce from Russell Brand. "I became depressed and I did not want to get out of bed. In the past, I had been able to overcome it, but this time something happened that made me fall down too many flights of stairs. I had to really go on a mental health journey," she told Vogue India.
She credited Orlando Bloom for saving her from downward spiral. "Orlando is like a sage. When we first met, he said we would pull the poison out of each other," she said "I've never had a partner who was willing to go on an emotional and spiritual journey like Orlando. It's challenging, because you're facing all the things you don't like about yourself."