Steinmeier, who is well-liked and respected across the political spectrum in Berlin, also served as vice-chancellor after Angela Merkel became German leader during their "grand coalition" government 2005-9.
A loyal party soldier, the affable but guarded protege of Merkel's charismatic predecessor Gerhard Schröder agreed to carry his Social Democrats' banner into battle against her in 2009.
His lacklustre campaign, and his role as an architect of Schröder's Agenda 2010 of unpopular labour market reforms, handed the SPD its worst post-war result in a general election and banished them to the opposition.
But the party leadership was grateful to Steinmeier for taking on the kamikaze mission against the high-flying Merkel and elected him their parliamentary group leader.
A policy wonk by nature, the 57-year-old Steinmeier spent much of his political career behind closed doors, honing his skills as a technocrat as he climbed the greasy pole one appointment at a time.
Schröder made Steinmeier one of his closest advisors during his seven years in power,and eventually his chief of staff, a job in which he coordinated the security services and shaped signature economic reforms.
The unpopular "Agenda 2010" job market measures were the centrepiece of the administration, successful in driving down unemployment but also a key factor in the party's bitter and lasting divide between centrists and leftists and its ongoing weakness in the polls.
A student of law with a cautious streak, Steinmeier finds it difficult to speak in media-friendly soundbites, preferring measured statements with elliptical German sentences that trail off far from where they started.
More a civil servant than a glad-handing politician, his charm works better in smaller, relaxed contexts where his dimpled smile and genuine interest in people can be used to the fullest.
"I never intended to become a politician," the prematurely white-haired Steinmeier told glossy magazine Bunte. "These things just happen sometimes."
Born on January 5th in 1956 in a small town in Lower Saxony, Steinmeier was known on the football field as an efficient "all-rounder" who could play any position with ease and work well within a team.
The same qualities led Schroeder to take him under his wing, first as media advisor when he was premier of Lower Saxony and later as a state secretary at the chancellery until making him his chief of staff in 1999.
As foreign minister, he repeatedly fought to defend his remit against Merkel's encroachment.
They clashed openly about Russia and China, with Steinmeier warning against alienating either country with too strident criticism and famously accusing her of pursuing a foreign policy comprised of "window-dressing" with little substance.
And his overtures toward Syrian President Bashar al-Assad while he was still seen as a reformist moderate in many capitals raised the ire of the conservatives.
Steinmeier tried to bolster Germany's "soft power" with cultural diplomacy, occasionally inviting painters, musicians and novelists to join him on official visits abroad.
Married with a teenage daughter, Steinmeier is protective of his private life. But he made headlines in 2010 when he withdrew temporarily from politics to
donate a kidney to his ailing wife, judge Elke Buedenbender.
He has since beat the drum to address a chronic lack of organ donors in Germany.