Smith, who is married to actor Will Smith, did not say to what she was addicted, or when and how she dealt with the problem.
Instead, she focused on the wisdom the experience helped her acquire.
"What I learned about myself is this, when I was younger I was not a good problem solver, meaning I had a very difficult time with dealing with my problems in life," E! News quoted her as writing.
"But today, at 42, I have my wisdom, my heart and my conscience as the only tools to overcome life's inevitable obstacles. I have become a good problem solver with those tools, and I am damn proud," she said. "What I hope is that we all continue to gain healthy understanding that life is really about, solving problems, and also about us learning to become masters at solving them."
E! News said Pinkett Smith's post follows months of speculation she and her husband are headed for divorce after 16 years of marriage.