Lancashire Police said the retired player was found in Liverpool after going missing from Preston on Thursday afternoon, and thanked the public for sharing an appeal.
The force tweeted: "Great news folks. Clarke Carlisle has been found safe in Liverpool. Thanks to everyone who shared our appeal. Have a good weekend."
The 37-year-old had last been seen by a family member in Preston on Thursday, sparking concern.
The former Professional Footballers' Association chairman, who made more than 500 appearances for nine clubs during his playing career, has a history of mental illness.
He launched a mental health charity called the Clarke Carlisle Foundation for Dual Diagnosis - a condition that has been described as "mental health problems co-occurring with drug or alcohol misuse".
The father-of-three remarried earlier this year and has worked to raise awareness of mental health issues.
The former defender tried to take his own life in December 2014 when he jumped into the path of a 12-ton lorry on the A64, near York, while suffering from depression.
His pregnant wife Carrie said: "Clarke has been found. Due to you all who have so kindly looked for him and shared he was missing. We all owe you a debt of gratitude."
He spent the 2004-5 season with Leeds United and had a spell at York City later on in his career.