Irish rugby dominated in the northern Hemisphere in 2009 and O'Driscoll not only led the national side to a first Grand Slam in 61 years, but also through an unbeaten season which included a November victory over World Cup and Tri Nations champions South Africa.
Although the 30-year-old Dubliner was not able to travel to the Tower Hotel in London to receive his award in person, he sent a video message to the 500-strong gathering which included a tribute to 2009 Lions coach Sir Ian McGeechan, who received a special award for his services to the game from the Rugby Union Writers' Club.
O'Driscoll said: "It feels pretty good to be in such great company (with the previous winners). Obviously, I thank the Rugby Writers' Club for the award.
"With any individual award when you play a team sport, you have to share it with your team-mates.
"All the sides I've been involved with, Leinster and Ireland with the successes, and even during the summer, the disappoinement with the Lions. I made a lot of good friendships there and played with some great players, so I share this award with all of them."
Click here to watch an interview with Brian confirming him as the award winner, taking a look back at his 2009 campaign and getting his thoughts on Ireland going forward and the special qualities of Sir Ian McGeechan.
First formed in 1960, the RUWC instituted the Pat Marshall Memorial award in the 1975/76 season in memory of the great Daily Express rugby writer.
PAT MARSHALL MEMORIAL AWARD WINNERS:
1975/76: Mervyn Davies (Swansea/Wales)
1976/77: Andy Irvine (Heriot's FP/Scotland)
1977/78: Gareth Edwards (Cardiff/Wales)
1978/79: JPR Williams (Bridgend/Wales)
1979/80: Bill Beaumont (Fylde / England)
1980/81: Jean-Pierre Rives (Toulouse/France)
1981/82: Ollie Campbell (Old Belvedere/Ireland)
1982/83: Dave Loveridge (Taranaki / New Zealand)
1983/84: Jim Aitken (Gala/Scotland)
1984/85: Mick Doyle (Ireland coach)
1985/86: Jonathan Davies (Neath/Wales)
1986/87: David Kirk (Auckland/New Zealand)
1987/88: Rob Norster (Cardiff/Wales)
1988/89: Finlay Calder (Stewart's-Melville FP/Scotland)
1989/90: Ian McGeechan (Scotland coach)
1990/91: David Campese (NSW/Australia)
1991/92: Nick Farr-Jones (NSW/Australia)
1992/93: Ben Clarke (Bath/England)
1993/94: Francois Pienaar (Transvaal/South Africa)
1994/95: Jonah Lomu (Counties/New Zealand)
1995/96: Sean Fitzpatrick (Auckland/New Zealand)
1996/97: Lawrence Dallaglio (London Wasps/England)
1997/98: Nick Mallett (South Africa coach)
1998/99: Tim Horan (Queensland/Australia)
1999/00: Pat Lam (Northampton Saints/Samoa)
2000/01: Martin Johnson (Leicester Tigers/England)
2001/02: Martin Johnson (Leicester Tigers/England)
2002/03: Jonny Wilkinson (Newcastle Falcons/England)
2003/04: Martin Johnson (Leicester Tigers/England)
2004/05: Rob Howley (London Wasps/Wales)
2005/06: Gareth Thomas (Toulouse/Wales)
2006/07: Jason White (Sale Sharks/Scotland)
2007/08: Jason Robinson (Sale Sharks/England)
2008/09: Shane Williams (Ospreys/Wales)
2009/10: Brian O'Driscoll (Leinster/Ireland)