Gunners boss Arsene Wenger could again utilise some of his fringe players when the npower Championship side come to Emirates Stadium for Saturday's fifth-round tie, with the likes of Jack Wilshere and captain Thomas Vermaelen both carrying injury concerns ahead of the Champions League showdown with Bayern Munich.
Walcott, though, maintains whichever 11 is sent out against Rovers, they must produce the required display to keep Arsenal on course for Wembley.
"A lot of players are back from international duty and need a bit of a break, so some may be rested for the FA Cup game, but that's just as important as we want to go far in that competition," Walcott said on the club's official website.
The Gunners battled to a 1-0 win at Sunderland, where full-back Carl Jenkinson was sent off for two cautions and so will be suspended against Blackburn.
The victory edged Arsenal up into fifth to stay within striking distance of arch-rivals Tottenham, whom they face at White Hart Lane in a fortnight.
Walcott feels his team have the strength of character needed to come through the challenges ahead.
"We are very confident [of finishing in the top four]. We can battle through any sort of situation," he said.
"The teams around us are winning as well, but we have just got to make sure we look after ourselves and try to win as often as we can.
"We will see where we are at the end of the season, but we have got to show the belief we did at Sunderland.
"I felt there were a lot of winners in that dressing room and the boys were fantastic."
Wilshere was withdrawn during the second half at Sunderland as a precaution and the England midfielder is expected to recover from a dead leg in time for the visit of Bayern.
Vermaelen, meanwhile, is understood to have been receiving injections to alleviate and ankle problem which has seen the Belgian miss the last two matches.
Defender Laurent Koscielny pulled out of the warm-up at Sunderland because of a calf problem suffered on international duty with France, and is another who will be closely monitored.
With Jenkinson suspended, Kieran Gibbs still sidelined by a thigh problem and Andre Santos having joined Brazilian side Gremio on loan, Wenger has seen his defensive options stretched.
Ignasi Miquel, the 20-year-old Spaniard, came on for the closing stages at Sunderland and looks set to be involved again this weekend.
Arsenal, meanwhile, are reported to have sent a scout to watch Victor Wanyama at Celtic on Tuesday night where the Bhoys were beaten 3-0 by Juventus in the first leg of their Champions League last-16 clash.
Wenger is known to be keen to bring in another defensive midfielder, having failed in a deadline-day move for Etienne Capoue of Toulouse.