Petter had previously been head of corporate media relations at the bank, having joined Lloyds at the start of this year.
Before joining Lloyds he was senior director, corporate relations at McDonald's Europe and global external relations manager, climate change and energy and materials at McKinsey & Company.
Prior to this he worked at Blue Rubicon and was a news producer at the BBC for 7 years.
He will report to the group corporate affairs Director Matt Young, who also joined Lloyds earlier this year from Santander.
Former group comms director Brigitte Trafford left her role in March after new CEO and former head of UK banking at Santander Antonio Horta-Osorio brought Young to Lloyds with him. She is now director of corporate affairs at ICAP.