The Edinburgh-based financial services firm chose Tulchan from a shortlist of four City firms, understood to have included former incumbent Maitland.
The company confirmed the appointment, with head of media relations Barry Cameron praising Tulchan's 'impressive market insight, comms expertise and creativity'.
Cameron added: 'Standard Life and Maitland have worked together for more than five years, and we would like to thank them for their support and hard work.'
It is understood that a key motivation for the repitch was board-level changes in personnel and strategy.
In June, Standard Life appointed its first full-time UK chief executive since January 2008, promoting 'take to market' director Paul Matthews.
In addition to Tulchan's appointment, the firm is also understood to have changed its corporate brokers.
Tulchan founder Andrew Grant said: 'The company has embarked upon a period of dynamic change in which its financial comms will play an important role. We look forward to making a valuable contribution to that process.'
The agency will work alongside Cameron and Graeme McEwan, Standard Life's group director of comms.
The firm, which embarked on a cost-cutting and redundancy programme in late 2010, reported in April a 25 per cent growth in first quarter sales, largely driven by growth in corporate pension schemes.
Meanwhile, Tulchan last week announced the hire of Ed Orlebar, who joined the agency as a consultant from M:Communications. He spent five years at M: after joining from Finsbury and was previously a financial journalist at Bloomberg.
James Macey White also joined as an associate from FD, where he was a vice-president.