Eger completed the tournament at 17-under-par 199. Tom Kite, a seven-time winner on the Champions Tour, also posted a Sunday 67 to take second place at 14-under-par 202.
Brad Bryant and John Harris posted matching rounds of 3-under 69 to share third place at 13-under-par 203. Morris Hatalsky, who shared the second-round lead with Eger and Craig Stadler, closed with an even-par 72 to end alone in fifth at minus-12.
Eger ran home a 20-foot birdie putt on the par-4 third and made it two straight as he birdied the fourth from 15 feet away to get to minus-14 at the Jack Nicklaus-designed TPC at Snoqualmie Ridge.
The 2003 MasterCard Classic winner padded his lead with a birdie on the par-3 sixth. Eger came back two holes later to birdie No. 8 from 6 feet out to move to 16 under, four shots clear of the field.
Eger notched his lone back nine birdie on the 11th and the 53-year-old cruised home with seven straight pars.
'Kite made a semi-charge, but neither Morris Hatalsky or Craig Stadler did,' Eger said. 'I just tried to avoid trouble on the back nine. I'm surprised no one made a run, I thought someone would throw in a 64 or so.'
Kite started his round with a birdie at the first, but tripped to a bogey at the next. The 55-year-old parred his next four holes before a birdie on the seventh.
The Texan parred five in a row around the turn before catching fire. He birdied the 13th and made it two straight as his birdie try on the par-4 14th found the bottom of the cup.
Kite then birdied the par-5 15th to cap a run of three straight birdies. After a pair of pars, he birdied the last to end alone in second.
'It's neat when you're 55 and you can still enjoy playing,' Kite said. 'I didn't get off to a good start. We needed a quick start and didn't get it.'
Stadler struggled with his swing all day long and his score reflected those troubles. He stumbled to a 1-over 73 to end alone in sixth at 11-under-par 205. Bruce Summerhays and Hale Irwin, the Champions Tours all-time wins leader, shared seventh at minus-10.
Don Pooley, two-time winner this season Dana Quigley, Senior PGA Champion Mike Reid and Dave Stockton tied for ninth at 8-under-par 208.