Former South Africa captain Elgar joins English county Essex
Elgar ended his time as a South Africa player earlier this month after 86 Tests and over 5,000 runs for the Proteas.
His final international appearance last week saw him captaining the Proteas who crashed to a seven-wicket defeat against India in Cape Town in a game that lasted just 642 balls - the shortest completed match in Test history.
The left-handed batsman was an English County Championship winner with Surrey in 2018 and has also represented Somerset with whom he had been linked again this time.
He will fill the void at Essex left by the retirement of former England captain Alastair Cook at the end of last season.
"I'm thrilled to embark on this new chapter of my cricketing journey with Essex," Elgar said on Friday after signing a three-year contract with the team.
"The club have been pushing for honours in recent years and I'm eager to contribute to further success.
"I've thoroughly enjoyed my previous experiences in county cricket and I'm really looking forward to joining up with the squad ahead of the season."
Essex finished as County Championship runners-up behind Surrey last season.
Essex head coach Anthony McGrath added: "He has had an outstanding career in Test cricket and has demonstrated to the world his desire to score runs at the highest level, right up until he retired.
"His achievements in the international arena speak volumes about his capabilities and we are excited to witness his impact at Essex."